JAT2916-published on line-19 Sept 2013

Differential responses to JNJ-37822681,
a specific and fast dissociating dopamine
D2 receptor antagonist, in cynomolgus
monkey and Sprague–Dawley rat general
toxicology studies: clinical observations,
prolactin levels, mammary histopathology
findings and toxicokinetics
Eric J. de Waala
*, Maria Desmidta
, Sven Korteb
, Marc Niehoffb
,
Kevan Chasec
, Wayne Arrowsmithc
and Ann Lampoa
ABSTRACT: JNJ-37822681 is a potent, specific and fast dissociating dopamine D2 receptor antagonist intended for the
treatment of schizophrenia. Its nonclinical toxicological profile was investigated in a series of general repeat dose toxicity
studies in cynomolgus monkeys and Sprague–Dawley rats. The maximum duration of treatment was 9 and 6 months, respec-
tively. Interspecies differences were noted in the response to JNJ-37822681 in terms of extrapyramidal (EPS)-like clinical signs
and prolactin-mediated tissue changes in the mammary gland. Monkeys showed severe EPS-like clinical signs such as
abnormal posture, abnormal eye movements and hallucination-like behavior at relatively low exposures compared to those
associated with EPS in patients with schizophrenia. The high sensitivity of the monkey to JNJ-37822681-induced EPS-like
signs was unexpected based on the fast dissociating properties of the compound. Rats, however, were not prone to EPS.
Elevated serum prolactin levels were found in rats and monkeys. While rats showed slight to moderate prolactin-related
tissue changes upon histopathological examination in all studies, which among others affected the mammary gland, only
minor mammary gland tissue changes were noted in monkeys. Prolactin levels were only slightly increased in patients with
schizophrenia receiving relatively high dose levels of JNJ-37822681. The monkey toxicology studies did not provide an
exposure-based safety margin, while in rats adverse effects were only noted at exposures considerably higher than those
achieved at efficacious plasma concentrations in the clinic. Overall, the available data suggest that the cynomolgus monkey
showed better predictivity towards the nature of JNJ-37822681-associated adverse events in humans than the Sprague–
Dawley rat. Copyright © 2013 John Wiley & Sons, Ltd.
Keywords: JNJ-37822681; antipsychotic; dopamine D2 receptor antagonist; extrapyramidal symptoms; EPS; prolactin; monkey; rat
Introduction
Schizophrenia is a common and debilitating mental illness. It is
characterized by positive symptoms (e.g., hallucinations, delu-
sions) and negative symptoms (e.g., apathy, poverty of speech,
social withdrawal) along with cognitive deficits (e.g., disorga-
nized and slow thinking, poor concentration) (Andreasen, 2000;
Reddy et al., 2012). It has been hypothesized that in particular
the positive symptoms are due to hyperactivity of the dopami-
nergic signal transmission in the brain (Strange, 2008). Accord-
ingly, antagonism at the dopamine D2 receptor is a common
mechanism of currently available medications for the treatment
of schizophrenia (Reddy et al., 2012). In the 1950s, the “typical”
or first generation antipsychotic drugs such as haloperidol and
chlorpromazine were introduced (Pierre, 2005; Seeman, 2006;
Strange, 2008). These drugs predominantly antagonize the
dopamine D2 receptor. Their side effect profile is mainly
characterized by the occurrence of extrapyramidal symptoms
(EPS) because of disturbed dopamine neurotransmission
(Miyamoto et al., 2005; Seeman, 2006). Presentations of EPS in
patients include parkinsonism (muscular rigidity, tremors and a
shuffling gait), dystonia (peculiar involuntary postures), akinesia
*Correspondence to: Eric de Waal, Janssen Research and Development, Drug
Safety Sciences, Turnhoutseweg 30, 2340 Beerse, Belgium. Email: edewaal@its.
jnj.com
a
Janssen Research and Development, a division of Janssen Pharmaceutica NV,
Drug Safety Sciences, Department of Preclinical Project Development,
Turnhoutseweg 30, 2340 Beerse, Belgium
b
Covance Laboratories GmbH, Kesselfeld 29, Münster, Germany
c
Huntingdon Life Sciences, Huntingdon Research Centre, Woolley Road,
Alconbury, Huntingdon, Cambridgeshire, PE28 4HS, UK
J. Appl. Toxicol. 2013 Copyright © 2013 John Wiley & Sons, Ltd.
Research Article
Received: 30 April 2013, Revised: 5 July 2013, Accepted: 5 July 2013 Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI 10.1002/jat.2916

(immobility), akathisia (restlessness manifested by the inability
to sit still or remain motionless for several minutes) and/or
tardive dyskinesia (involuntary repetitive movements) (Pierre,
2005; Reddy et al., 2012; Sachdev and Brüne, 2000; Strange,
2008). Subsequently the “atypical” or second generation of anti-
psychotics, including clozapine, quetiapine, risperidone and
olanzapine was introduced (Gründer et al., 2009). Atypical anti-
psychotics have a more diverse pharmacological profile than
typical ones due to multiple receptor affinities. In general, they
possess a higher affinity to the serotonin 5-HT2 receptor relative
to the dopamine D2 receptor. Atypical antipsychotics such as
risperidone and olanzapine show a lower propensity for EPS
than typical antipsychotic drugs, while EPS is virtually absent
with clozapine and quetiapine (Auclair et al., 2009; Miyamoto
et al., 2005, Pierre, 2005; Seeman, 2006; Strange, 2008). Whereas
typical antipsychotics raise serum prolactin levels secondary to
their dopamine D2 receptor antagonistic action, most atypicals
are less prone to induce sustained hyperprolactinemia (Kapur
& Remington, 2001; Kapur & Seeman, 2001). Consequently,
atypical antipsychotics raise less concern for prolactin-mediated
side effects that manifest in humans as menstrual disturbances,
galactorrhea, sexual dysfunction and/or decreased fertility
(Dickson & Glazer, 1999; Goodnick et al., 2002). On the other
hand, in humans atypicals are associated with other distressing
side effects such as weight gain, hyperglycemia and
dyslipidemia collectively designated as metabolic syndrome
(Boyda et al., 2010; Miyamoto et al., 2005; Strange, 2008).
The “serotonin–dopamine” hypothesis proposes that the
unique feature of an atypical antipsychotic drug is its greater
affinity to bind to the serotonin 5-HT2 than the dopamine D2
receptor (Casey, 1993; Kapur & Remington, 2001; Strange,
2008). However, it has been observed that atypical antipsychotic
drugs with low EPS liability in humans such as clozapine and
quetiapine have the fastest rate of dissociation from the
dopamine D2 receptor, whereas atypical antipsychotics associ-
ated with a high prevalence of EPS are the slowest dissociating
dopamine D2 antagonists (Langlois et al., 2012). To explain this,
the “fast-off-D2” theory hypothesizes that clozapine and
quetiapine continuously go on and off the receptor rapidly,
allowing extensive and frequent access of endogenous dopa-
mine to the receptor. This leads to a low level of D2 receptor
occupancy, and a more physiological dopamine transmission.
These characteristics also clarify why clozapine does not give rise
to EPS and sustained prolactin elevations. In contrast, typical
antipsychotics such as haloperidol bind tightly to the receptor
and elicit EPS and marked hyperprolactinemia. This theory
implies that while the dopamine D2 receptor is essential to the
atypical antipsychotic action, the serotonin 5-HT2 receptor is
not. In fact, atypical antipsychotics differ from typicals by their
lower affinity to the D2 receptor rather than by their higher
affinity at 5-HT2 (Kapur and Remington, 2001; Kapur and
Seeman, 2001; Seeman, 2006).
JNJ-37822681 (N-[1-(3,4-difluorobenzyl)piperidin-4-yl]-6-
(trifluoromethyl)pyridazin-3-amine) is a potent, specific and fast
dissociating D2 receptor antagonist. This compound was
designed with the aim of combining fast dissociating properties
with specificity for D2 receptors to avoid side effects caused by
current antipsychotics in patients with schizophrenia (Langlois
et al., 2012). Its dissociation rate from the human D2 receptor
(half-life t½ 3.7 s at 37 °C) is faster than that of haloperidol
(24.5 s) and risperidone (49.2 s), and similar to that of clozapine
(5.8 s). The subcutaneous ED50 value (i.e., the dose producing
50% responders) for in vivo D2 receptor occupancy in male
Wistar–Wiga rats (0.39 mg kg–1
body weight) is close to the
subcutaneous ED50 value of 0.19 mg kg–1
for inhibition of ste-
reotypic behavior (i.e., compulsive sniffing, licking and chewing)
induced by the dopamine agonist apomorphine in male Wistar–
Wiga rats, an important animal model of antipsychotic activity.
In rats, JNJ-37822681 induces minimal prolactin release at the
lowest dose levels required for central D2 receptor blockade.
Relative to the antagonism of apomorphine-induced stereo-
typy, JNJ-37822681 showed a large, 42-fold specificity margin
for the induction of catalepsy in rats, exceeding that obtained
for haloperidol and at least as large as that measured for atypi-
cal antipsychotics (Langlois et al., 2012). Catalepsy in rats is a
condition characterized by muscular rigidity and a fixed body
posture unresponsive to external stimuli. It is generally consid-
ered predictive of EPS liability in humans (Hoffman &
Donovan, 1995). Therefore, the wide 42-fold margin supports
the hypothesis that fast dissociation from the D2 receptor
decreases EPS liability and can make specific D2 antagonists in
terms of EPS behave similarly to multireceptor atypical antipsy-
chotics (Langlois et al., 2012).
A recent 12-week phase 2B trial of JNJ-37822681 showed
antipsychotic efficacy in patients with schizophrenia with an
acute exacerbation of their illness at oral dose levels of 10, 20
and 30 mg twice daily (Anghelescu et al., 2012; Schmidt et al.,
2012). Other investigations with JNJ-37822681 included a [11
C]
raclopride positron emission tomography trial in healthy volun-
teers demonstrating dose-dependent D2 receptor occupancy
(te Beek et al., 2012a) and a single ascending dose (SAD) trial
in healthy volunteers focusing on safety, pharmacokinetics and
central nervous system effects (te Beek et al., 2012b).
In this paper, we document the nonclinical toxicological
profile of JNJ-37822681 in cynomolgus monkeys and Sprague–
Dawley rats as investigated in a series of general toxicology
studies up to 9 and 6 months of duration, respectively. These
studies were conducted to meet regulatory requirements for
nonclinical safety studies in support of clinical trials (ICH, 1998,
2009). Interestingly, differences were noted in the response to
JNJ-37822681 between monkeys and rats in particular with
respect to EPS-like clinical signs and hyperprolactinemia.
Materials and methods
Test facilities and animal welfare considerations
A series of toxicology studies with JNJ-37822681 was conducted
at test facilities of the Sponsor, Johnson & Johnson
Pharmaceutical Research & Development, a division of Janssen
Pharmaceutica NV (Beerse, Belgium), and by order of the
Sponsor at Covance Laboratories GmbH (Münster, Germany),
Covance Laboratories Ltd. (Harrogate, UK) and Huntingdon Life
Sciences Ltd. (Alconbury, Huntingdon, UK). All four test facilities
were approved by the Association for Assessment and Accredi-
tation of Laboratory Animal Care International (AAALAC). The
studies conducted at Covance Laboratories and Huntingdon Life
Sciences were performed in accordance with the requirements
of the Animal (Scientific Procedures) Act 1986. The studies at
Covance Laboratories GmbH, were performed in compliance
with German animal welfare law. In the studies conducted at
Janssen Pharmaceutica NV, all animals were treated humanely
and cared for in accordance with the European and Belgian
guidelines, and principles of euthanasia by the American
E. J. de Waal et al.
J. Appl. Toxicol. 2013Copyright © 2013 John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/jat

Veterinary Medical Association. All experimental protocols were
approved by institutional review committees in each test facility.
In all studies, the animals were housed in climate-controlled
rooms under routine test conditions of temperature, relative
humidity, ventilation and illumination.
Good Laboratory Practice compliance
Except for the tolerability studies, all studies were conducted in
compliance with Good Laboratory Practice regulations issued
by the Organization of Economic Co-operation and Develop-
ment (OECD, 1997).
Studies in cynomolgus monkeys
Experiment 1. Tolerability study in monkeys
Test facility and test material. The monkey tolerability study
was conducted at Covance Laboratories GmbH. The test
material, JNJ-37822681 base was provided by the sponsor,
dissolved in purified water adjusted to pH 3.0 ± 0.1, and dosed
by oral gavage at a dose volume of 5 mL kg–1
.
Animals. Male and female purpose-bred cynomolgus monkeys
(Macaca fascicularis) of Chinese or Vietnamese origin were
obtained from a recognized suppler. They were in the weight
range 3.5–6.5 kg and in the age range 2.5–8 years at predose.
The animals were single housed by sex. Tools for environmental
enrichment were provided. The animals were offered twice daily
a commercial pellet diet for non-human primates (Ssniff P10,
Ssniff Spezialdiäten GmbH, Soest, Germany). The animals regu-
larly received fresh fruit and bread. They received a tasty reward
after each handling or manipulation. Tap water was provided ad
libitum except during urine collection.
Experimental design. One male and one female animal were
assigned to the single dose escalation phase where they
received a single dose of JNJ-37822681 at 0 (vehicle control), 1,
3, 10 or 20 mg kg–1
. In between dose administrations, the
wash-out period was 7–9 days. After termination of this initial
phase and a wash-out period of 10 days, the same animals were
also used for the subsequent 5-day repeat dose phase together
with one additional male and female animal. In the latter phase,
all four animals were dosed at 20 mg kg–1
day–1
for 5 consecu-
tive days.
Parameters. Mortality, clinical signs, body weight, routine
hematology, clinical chemistry and urinalysis parameters
were evaluated in both study phases. Electrocardiographic
and blood pressure measurements were conducted during
the repeat dose phase. Blood samples were collected after
termination of the single escalating dose phase and the
repeat dose phase and analyzed for serum prolactin with a
DSL kit. For toxicokinetic purposes, blood samples were
collected in EDTA at predose, 30 min, and at 1, 2, 4, 8 and
24 h after each dose administration in the single escalating
dose phase and after the first and last dose administration
in the repeat dose phase. The latter plasma samples were an-
alyzed for JNJ-37822681 by a qualified research method. At
the termination of the repeat dose phase, the animals
received ketamine and pentobarbitone before exsanguina-
tion. A macroscopic pathology examination was conducted.
A limited number of tissues were examined microscopically.
Experiment 2. One-month repeat dose toxicity study in monkeys
Test facility and test material. The 1-month monkey study was
conducted at Covance Laboratories Ltd. The test material, JNJ-
37822681 dihydrochloride salt, was provided by the sponsor,
dissolved in purified water, and dosed by oral gavage at a dose
volume of 5 ml kg–1
. A salt to base conversion factor of 1.21 was
applied to express the dose levels in mg equivalents (eq.)kg–1
body weight day–1
.
were obtained from a supplier in Mauritius. The animals were
80–114 weeks of age and in the weight range of 2.17–2.6 kg
(males) and 2.16–2.4 kg (females) at the initiation of treatment.
They were 80–114 weeks old at the start of dosing. Animals of
the same group and sex were housed together. Food was
offered communally. Each animal was offered approximately
100 g of SQC Mazuri Primate Diet (Special Diets Services Ltd.,
Witham, Essex, UK) and a 25 g Bonio biscuit (Spillers, Nestlé).
They also were given daily supplements of fresh fruit, fruit drink,
vegetables, peanuts, sunflower seeds or forage mix. Mains water
was provided ad libitum.
Experimental design. Groups of three animals per sex initially
received JNJ-37822681 at 0 (vehicle control), 1.25, 5 or 20 mg eq.
kg–1
day–1
. These dose levels were selected based on the out-
come of the preceding monkey tolerability study (experiment
1). During the 1-month treatment course, the dose levels of
JNJ-37822681 were repeatedly adjusted and consequently the
treatment phase was prolonged up to 43 days as summarized
in Table 1.
Parameters. The animals were observed daily for mortality and
clinical signs. Electrocardiographic and heart rate measurements
as well as ophthalmic examinations were performed pre-treatment,
and in week 6. Food consumption was evaluated daily. Routine
hematology, clinical chemistry and urinalysis parameters were
evaluated in weeks 4 and 6. Blood samples were collected at 1, 2,
4, 8 and 24 h after dosing on days 1, 8, and 42, and at 2 h after
dosing on day 15. Serum prolactin levels were measured in these
samples, and prolactin AUC0-24 h values calculated. Blood samples
for toxicokinetic analysis were collected in EDTA from all animals
on days 1, 8 and 42 at 0.5, 1, 2, 4, 8 and 24 h postdose. Plasma levels
of JNJ-37822681 were measured by a validated LC-MS/MS method.
Following sedation with ketamine, each animal was killed at the
end of the treatment period by intravenous injection of an over-
dose of sodium pentobarbitone and exsanguinated. Postmortem
examinations included weighing of organs, and full macroscopic
and microscopic pathology.
Table 1. Dose levels of JNJ-37822681 employed in the 1-
month repeat dose toxicity study in cynomolgus monkeys
Group
number
Day 1a
Day 8a
Days 15–29 Days 30–43
Dose level (mg eq. kg–1
[day–1
])
1 0b
0b
0b
0b
2 1.25 0.63 0.16 0.32
3 5 2.5 0.63 1.25
4 20 10 2.5 5
a
Single dose administration. b
Vehicle control.
JNJ-37822681 toxicological profile in rats and Cynomolgus monkeys
J. Appl. Toxicol. 2013 Copyright © 2013 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/jat

Experiment 3. Three-month repeat dose toxicity study with a
1-month recovery phase in monkeys
conducted at Covance Laboratories GmbH. The test material,
JNJ-37822681 dihydrochloride salt, was provided by the spon-
sor, dissolved in purified water, and dosed by oral gavage at a
dose volume of 5 ml kg–1
. A salt to base conversion factor of
1.21 was applied to express the dose levels in mg eq. kg–1
body
weight day–1
.
were obtained from a supplier in Mauritius. The animals were ap-
proximately 3 years of age and in the weight range 2.9–4.2 kg
(males) and 2.8–3.7 kg (females) at the initiation of treatment.
Animals of the same sex were pair- or grouped-housed (except
during urine collection). Tools for environmental enrichment
were provided. A commercial pellet diet for non-human
primates was offered twice daily (Ssniff P10, Ssniff Spezialdiäten
GmbH). Tap water was provided ad libitum. The animals
regularly were given fresh fruit and bread. They received a tasty
reward after each handling or manipulation.
Experimental design. Groups of three animals per sex initially
received JNJ-37822681 at 0 (vehicle control), 0.1, 0.3 and 1 mg
eq. kg–1
day–1
. In addition, two animals per sex were allocated
to the control and high-dose groups and were assigned to a 4-
week treatment-free recovery period. The dose levels were
based on the outcome of the preceding 1-month monkey study
(experiment 2). During the course of the study, the dose levels of
JNJ-37822681 were repeatedly adjusted. The various dose
administrations are summarized in Table 2.
Parameters. All animals were observed daily for mortality and
clinical signs. The body temperature of the high-dose animals
was measured on day 37 at 4, 8 and 24 h postdose. Body weight
was recorded once weekly. Electrocardiographic and blood pres-
sure measurements were performed in all animals pre-treatment,
in weeks 6 and 13 of treatment (about 2–4 h postdose), and at
the end of recovery. Ophthalmic examinations were conducted
pre-treatment, in week 13, and at the end of recovery. Routine
hematology, clinical chemistry and urinalysis parameters were
evaluated predose, in weeks 6 and 12, and at the end of recovery.
Blood samples were collected at 0 (predose), 1, 2, 4, 8 and 24 h
during the predose phase and after dosing in weeks 6 and 12,
and at the end of recovery. Serum prolactin levels were measured
in these samples, and prolactin AUC0–24 h values calculated. For
toxicokinetic analysis, blood samples were collected in EDTA on
days 1, 14 and 91 at 0 (predose), 30min, and 1, 2, 4, 8 and 24 h
postdose. Limited blood sampling for toxicokinetics was also
conducted on days 13 (0 [predose], 2 and 4, and 8 h postdose),
29 (2h postdose) and 70 (0 [predose, 0.5, 1, 2, 4, 8 and 24h
postdose). In these samples, JNJ-37822681 was analyzed by a
validated LC-MS/MS method. At necropsy, the animals received
ketamine and sodium pentobarbitone before exsanguination.
Organ weights were recorded, and a full macroscopic and micro-
scopic pathology examination was conducted.
Experiment 4. Nine-month repeat dose toxicity study in monkeys
conducted at Huntingdon Life Sciences Ltd. The test material,
JNJ-37822681 monohydrochloride salt, was provided by the
sponsor, dissolved in purified water and dosed by oral gavage
at a dose volume of 1 ml kg–1
. A salt to base conversion factor
of 1.10 was applied to express the dose levels in mg eq. kg–1
body weight day–1
.
were obtained from a supplier in China (by R.C. Hartelust BV,
Tilburg, The Netherlands). The animals were approximately
34–59 months of age and in the weight range 3.2–5.5 kg
(males) and 2.1–3.0kg (females) at the initiation of treatment.
Animals were housed in pairs of the same sex and group per cage,
except for the period just before each administration until approx-
imately 1–2 h after dosing. The floor of each cage was covered with
sawdust for environmental enrichment. Each animal was offered
200g of a standard dry diet (Old World Monkey Diet) daily. Two
biscuit supplements and fresh fruit were provided on a daily basis
as well. Tap water was provided ad libitum except when urine was
being collected.
Experimental design. Groups of four animals per sex initially
received JNJ-37822681 at 0 (vehicle control), 0.1, 0.3 or 1 mgeq.
kg–1
day–1
. The dose levels were based on the outcome of the pre-
ceding 3-month monkey study (experiment 3). During the course
of the study, dose levels of JNJ-37822681 were gradually escalated.
The various dose administrations are summarized in Table 3.
Parameters. All animals were observed daily for mortality and
clinical signs. Body weight was recorded once weekly. Ophthal-
mic and electrocardiographic examinations as well as blood
pressure measurements were conducted pre-treatment, and at
weeks 13, 26 and 39. Routine hematology and clinical chemistry
parameters were evaluated predose, and at weeks 13, 26 and 39.
Urinalysis was conducted predose, and at weeks 12, 25 and 38.
Blood samples were collected at 0 (predose), 1, 2, 4, 8 and 24 h
during the predose phase and after dosing in weeks 26 and
39. Serum prolactin levels were measured in these samples by
radioimmunoassay. For toxicokinetic analysis, blood samples
Group
number
Days 1–13 Days 14–28 Days 29–70 Days 70–91
day–1
)
1 0a
0a
0a
0a
2 0.1 0.16 2.5 2.5
3 0.3 0.63 5 5
4 1 2.5 10 7.5
a
Vehicle control.
Group
number
Days 1–14 Days 15–42 Day 43 onwards
day–1
)
1 0a
0a
0a
2 0.1 0.3 0.6
3 0.3 0.75 1.5
4 1 2.5 5
a
Vehicle control.

were collected in EDTA at weeks 8 and 39 at predose, 30 min,
and 1, 2, 4, 8 and 24 h postdose. In these samples, JNJ-
37822681 was analyzed by a validated liquid chromatography-
tandem mass spectrometry (LC-MS/MS) method. At necropsy,
the animals were killed by an overdose of sodium pentobarbi-
tone and subsequent exsanguination. Organ weights were
recorded, and a full macroscopic and microscopic pathology
examination was conducted.
Studies in Sprague–Dawley rats
Experiment 5. Tolerability study in rats
Test facility and test material. The rat tolerability study was
conducted at Janssen Pharmaceutica NV. The test material, JNJ-
37822681 base, was dissolved in purified water adjusted to pH 3.0
± 0.1 and dosed by oral gavage at a dose volume of 1 mlkg–1
.
Animals. Male SPF Sprague–Dawley rats (Crl:CD® (SD) IGS) were
supplied by Charles River (Charles River Laboratories, Sulzfeld,
Germany). At the initiation of treatment, they were approxi-
mately 6 weeks of age and in the weight range 180–223 g. They
were housed individually. The diet consisting of powdered rat
food was provided ad libitum (SAFE, Les Tremblats, Augy,
France). The animals were given continuous access to water.
Experimental design. In the single dose phase, groups of five
male rats received JNJ-37822681 at dose levels of 0 (vehicle con-
trol), 20, 40 or 80 mg kg–1
. In the subsequent 5-day repeat dose
phase, six male rats were treated orally by gavage at 0 (vehicle
control), 20 or 80 mgkg–1
day–1
.
Parameters. Mortality, clinical signs, body weight were evalu-
ated in both study phases. Routine hematology and clinical
chemistry parameters, and serum prolactin levels were exam-
ined at the end of the repeat dose phase. For toxicokinetic pur-
poses blood samples were collected in EDTA on day 5 of the
repeat dose phase at 1, 4 and 24 h postdose (first three rats)
and at 2 and 8 h post-dose (last three rats). The plasma samples
were analyzed for JNJ-37822681 by a qualified research LC-MS/
MS method. At termination of the repeat dose phase, the
animals received pentobarbitone before exsanguination. A
macroscopic pathology examination was conducted. A limited
number of tissues was examined microscopically.
Experiment 6. One-month repeat dose toxicity study with a
1-month recovery phase in rats
Test facility and test material. The 1-month rat study was
conducted at Janssen Pharmaceutica NV. The test material, JNJ-
37822681 dihydrochloride salt, was dissolved in demineralized
water adjusted to pH 3.0 ± 0.1, and dosed by oral gavage at a
dose volume of 1 ml kg–1
. A salt to base conversion factor of
1.21 was applied to express the dose levels in mg eq. kg–1
body
weight day–1
.
Animals. Male and female SPF Sprague–Dawley rats (Crl:CD®
(SD) IGS) were supplied by Charles River. At the initiation of
treatment, they were approximately 6 weeks of age and in the
weight range 203–208 g (males) and 147–154 g (females). They
were housed individually. The diet consisting of powdered rat
food was provided ad libitum (SAFE), except before blood
sampling for hematological and serum analyses, before urine
sampling and killing. The animals were given continuous access
to water.
Experimental design. Groups of 10 animals per sex initially
received JNJ-37822681 at 0 (vehicle control), 5, 20 or 80 mg eq.
kg–1
day–1
. The dose levels were based on the outcome of the
preceding rat tolerability study (experiment 5). Five animals
per sex were added to the vehicle control and high-dose groups,
and allocated to a 1-month recovery period. For toxicokinetic
purposes, the study also included six satellite animals per sex
in each of the JNJ-37822681-dosed groups, and three satellite
animals per sex in the vehicle control group. Additionally five
animals per sex in the vehicle control and highest dose group
were allocated to 1-month treatment-free recovery phase after
the termination of the treatment period.
Parameters. Mortality, clinical signs, body weight, body weight
gain, food consumption, ophthalmoscopy, hematology, coagula-
tion, clinical chemistry, urinalysis, organ weights, macroscopic
and histopathology, including bone marrow cytology were
assessed. Serum prolactin levels were measured by an enzyme-
linked immunosorbent assay, rat prolactin ELISA (Biocode, Liège,
Belgium). Prolactin AUC0–24 h values were calculated. On days
0 and 27, blood in EDTA was sampled from the satellite animals
at 0.5, 2 and 7 h postdose for the first three male and female rats,
and at 1, 4 and 24 h postdose for the last three male and female
rats. Plasma levels of JNJ-37822681 were analyzed by a validated
LC-MS/MS method. Mean plasma concentrations were
calculated (n = 3) per day, per dose, per sex and per sampling
point. These results were subsequently used to calculate mean
AUC0–24 h values.
Experiment 7. Three-month repeat dose toxicity study in rats
conducted at Janssen Pharmaceutica NV. The test material,
JNJ-37822681 dihydrochloride salt, was dissolved in
demineralized water adjusted to pH 3.0 ± 0.1, and dosed by oral
gavage at a dose volume of 1 ml kg–1
. A salt to base conversion
factor of 1.21 was applied to express the dose levels in mg eq.
kg–1
body weight day–1
.
(SD) IGS) were supplied by Charles River. At the initiation of
treatment, they were approximately 6 weeks of age and in the
weight range 195–206 g (males) and 150–153 g (females). They
were group-housed. The diet consisting of R/M-H pelleted main-
tenance rat feed (Ssniff Spezialdiätn GmBH) and was provided
ad libitum, except before blood sampling for hematological
and serum analyses, before urine sampling and killing. The
animals were given continuous access to water.
kg–1
day–1
preceding 1-month rat study (experiment 6). For toxicokinetic
purposes, the study also included six satellite animals per sex
in each of the groups.
gain, food consumption, water consumption, ophthalmoscopy,
hematology, coagulation, clinical chemistry, urinalysis, organ
weights, macroscopic and histopathology were assessed. Serum
prolactin levels were measured by rat prolactin ELISA (Biocode).
Prolactin AUC0–24 h values were calculated. On days 0, 27 and 91,
blood in EDTA was sampled from the satellite animals at 0.5, 2
and 7 h postdose for the first three male and female rats, and
at 1, 4 and 24 h postdose for the last three male and female rats.

Plasma levels of JNJ-37822681 were analyzed by a validated LC-
MS/MS method. Mean plasma concentrations were calculated
(n = 3) per day, per dose, per sex and per sampling point.
These results were subsequently used to calculate mean
AUC0–24 h values.
Experiment 8. Six-month repeat dose toxicity study in rats
conducted at Huntingdon Life Sciences. The test material, JNJ-
37822681 monohydrochloride salt, was dissolved in purified wa-
ter, and dosed by oral gavage at a dose volume of 10 ml kg–1
. A
salt to base conversion factor of 1.10 was applied to express the
dose levels in mg eq. kg–1
body weight day–1
.
(SD) IGS) were supplied by Charles River Ltd., (Charles River UK
Ltd. is Manston Road, Margate, Kent CT9 4LT, United kingdom).
At the initiation of treatment, they were approximately 47 days
of age and in the weight range 227–232 g (males) and
178–185 g (females). They were group-housed. The animals were
allowed free access to a standard rodent diet (Rat and Mouse
No. 1 Maintenance Diet), except when urine was being collected
and overnight before routine blood sampling. Potable water
taken from the public supply was freely available, except when
urine was being collected.
kg–1
day–1
preceding 3-month rat study (experiment 7). For toxicokinetic
purposes, the study also included three satellite animals per
sex in each of the groups.
gain, food consumption, water consumption, ophthalmoscopy,
hematology, coagulation, clinical chemistry, urinalysis, organ
weights, macroscopic and histopathology were assessed.
On days 52 and 136, serum prolactin levels were measured
by rat prolactin ELISA (Biocode). Prolactin AUC0–24 h values
were calculated. During week 26, blood in EDTA was sampled from
the satellite animals at 1, 2, 4, 7 and 24h postdose. Plasma levels of
JNJ-37822681 were analyzed by a validated LC-MS/MS method.
Results
Studies in cynomolgus monkeys
Experiment 1. Tolerability study in monkeys
During the single escalating dose phase slight hypoactivity,
apathy and staggered movements were noted at 10 and 20 mg
kg–1
. No adverse clinical signs were noted at 1 or 3 mg kg–1
. At
the repeat dose phase at 20 mg kg–1
day–1
, slight hypoactivity,
apathy, hunched posture and tremors were observed. Serum
prolactin levels were increased 1.4–6.4-fold comparing blood
samples taken at predose and at termination of the repeat dose
phase. In the female mammary glands, a minimal to slight devel-
opment of tubular–alveolar glands and ducts was found. After
the fifth dose of 20 mg kg–1
day–1
in the repeat dose phase the
maximum plasma levels (Cmax values) of JNJ-37822681 were
1350 and 2550 ng ml–1
in the male, and 1570 and 1810 ng ml–1
in the female monkeys, respectively. The areas under the 24-h
plasma concentration–time curve (AUC0–24 h values) were 13
900 and 55 400 ng h–1
ml–1
in the male and 20 000 and 25
500 ng h–1
ml–1
in female animals, respectively.
Experiment 2. One-month repeat dose toxicity study in monkeys
After a single dose on day 1, excessive sleeping was noted at
1.25, 5 and 20 mg eq. kg–1
. At 20 mg eq. kg–1
on day 1, the ani-
mals were subdued, did not move, showed hunched posture
and sat as though in a trance. This behavior lasted up to 29 h
postdose. Tremors were also recorded. At 5 and 1.25 mg eq.
kg–1
, the animals were subdued until 21 and 8 h postdose,
respectively. Because of these adverse clinical signs, dosing
was suspended and the animals were given a wash-out period
of 1 week.
Treatment was restarted on day 8 at dose levels of 0.63, 2.5
and 10 mg eq. kg–1
. However, once again the animals showed
excessive drowsiness after a single dose administration. At
10 mg eq. kg–1
, the clinical signs resembled those observed pre-
viously at 20 mg eq. kg–1
. Furthermore, two male monkeys
dosed at 10 mg eq. kg–1
showed a stiff gait. One of the males
was noted to be in a trance-like state, while the remaining two
were rolling their heads and appeared to hallucinate. Dosing
Table 4. Mammary gland histopathology findings in the 1-month repeat dose toxicity study in cynomolgus monkeys
day–1
) 0a
0.32 1.25 5
Males
Number of animals examined
3 3 3 3
Number of animals affected
Prominent glandular development Minimal 0 0 0 0
Slight 0 0 0 0
Females
3 3 3 3
Prominent glandular development Minimal 1 2 2 1
Slight 0 0 1 1
a
Vehicle control.

was suspended again, and animals were given another wash-out
period of 1 week.
The study was restarted on day 15 at 0.16, 0.63 and 2.5 mg eq.
kg–1
. These dose levels could be maintained for 15 consecutive
days. At 0.63 and 2.5 mg eq. kg–1
day–1
impaired mobility, rigid-
ity, staring and/or fixated eyes were reported. The animals were
lying down, and reluctant to move even when disturbed. At
0.63 mg eq. kg–1
day–1
, a trance-like state was noted as well.
There were no clinical signs at 0.16 mg eq. kg–1
day–1
. Owing to
lessening clinical signs, on day 30 the dose levels could be
doubled to 0.32, 1.25 and 5 mg eq. kg–1
day–1
, respectively. The
latter dose levels were kept for the remainder of the study until
termination on day 42. At 5 mg eq. kg–1
day–1
, similar signs as
noted earlier at 2.5 mg eq. kg–1
day–1
occurred. In addition, some
animals adopted an unusual or abnormal posture. Single
animals dosed at 5 mg eq. kg–1
day–1
showed isolated incidents
of vomiting, eyes flickering, shaking, appearing to hallucinate,
being unable to hold onto the cage, falling repeatedly, stagger-
ing (ataxia), head shaking/flicking/rolling and excessive vocaliza-
tion. There were no notable decreases in the appearance of
clinical signs at this dose level. At 1.25 mg eq. kg–1
day–1
, the
animals showed signs comparable to those noted earlier at
0.63 mg eq. kg–1
day–1
. In addition, some animals were standing
like a statue, and showed an unusual posture. By the end of
dosing, a slight decline in the number and duration of these
signs was noted. At 0.32 mg eq. kg–1
day–1
, two males were
subdued and showed a hunched posture on day 42 only.
There was a minor increase in glandular development of the
female mammary gland at all dose levels as compared to
controls (Table 4). This finding was characterized by obvious
mammary acini and ducts, with cuboidal to columnar epithe-
lium, inflammatory cell infiltration and occasional signs of secre-
tion. Although these tissue changes still were within the normal
range expected for pubescent female monkeys, and prolactin
Table 5. Mean serum prolactin levels (± SEa
) in the 1-month repeat dose toxicity study in cynomolgus monkeys
Dose level
(mg eq.kg–
1
[day–1
])
1 h postdose
(ng ml–1
)
2 h postdose
(ng ml–1
)
4 h postdose
(ng ml–1
)
8 h postdose
(ng ml–1
)
24 h postdose
(ng ml–1
)
AUC1-24h
(ng h–1
ml–1
)
Males, day 0 (single dose)
0b
3.9 ± 0.43 2.7 ± 0.62 4.5 ± 1.7 3.2 ± 0.67 4.0 ± 0.71 85 ± 18
1.25 22.6 ± 5.8 12.8 ± 2.4 7.6 ± 1.9 1.9 ± 0.47 2.2 ± 0.90 101 ± 24
5 27.3 ± 9.2 14.2 ± 3.9 8.7 ± 5.8 4.3 ± 1.7 2.9 ± 0.90 144 ± 49
20 35 ± 5.3 22 ± 2.3 13 ± 0.4 8 ± 1.3 7 ± 1.0 243 ± 28
Females, day 0 (single dose)
0 5.3 ± 1.3 4.6 ± 0.5 6.0 ± 0.8 7.2 ± 1.3 6.5 ± 1.1 154 ± 25
1.25 57 ± 5.4 30 ± 0.3 11 ± 0.7 5 ± 0.8 5 ± 0.7 226 ± 16
5 78 ± 26 49 ± 16 18 ± 4.6 7 ± 0.2 7 ± 2.2 335 ± 96
20 33 ± 7.5 22 ± 2.4 10 ± 0.2 5 ± 0.3 5 ± 1.0 191 ± 3
Males, day 8 (single dose)
0 3.7 ± 0.8 3.2 ± 0.7 2.9 ± 0.5 2.6 ± 0.5 4.2 ± 1.1 77 ± 18
0.63 22.9 ± 5.6 11.7 ± 2.9 4.2 ± 1.4 2.1 ± 0.4 2.4 ± 1.1 93 ± 23
2.5 30.9 ± 9.0 20.3 ± 6.7 7.6 ± 2.8 5.4 ± 2.3 3.2 ± 1.2 164 ± 59
10 57 ± 7.5 32 ± 2.9 14 ± 0.7 8 ± 0.8 6 ± 1.1 275 ± 26
Females, day 8 (single dose)
0 6.2 ± 1.7 4.2 ± 0.8 4.4 ± 0.9 7.7 ± 2.8 10.0 ± 3.0 182 ± 56
0.63 79 ± 7.0 35 ± 4.1 11 ± 1.5 5 ± 0.5 6 ± 2.3 266 ± 39
2.5 100 ± 30 45 ± 14 16 ± 3.9 7 ± 2.1 7 ± 1.0 342 ± 87
10 62 ± 11 35 ± 5.8 12 ± 1.4 7 ± 0.4 5 ± 0.9 259 ± 25
Males, day 42 (repeat dosing)
0 2.6 ± 0.1 2.5 ± 0.1 2.8 ± 0.5 4.7 ± 1.5 5.3 ± 1.5 105 ± 29
0.32 15 ± 4.3 8.5 ± 1.7 3.1 ± 1.1 3.1 ± 1.2 4.0 ± 1.8 101 ± 36
1.25 28.7 ± 10 23.7 ± 2.9 9.6 ± 3.6 4.8 ± 2.0 3.4 ± 1.1 160 ± 57
5 62 ± 4.3 33 ± 1.8 19 ± 0.4 12 ± 1.8 8 ± 1.5 351 ± 30
Females, day 42 (repeated dosing)
0 4.3 ± 0.5 3.7 ± 0.7 5.3 ± 0.9 7.9 ± 2.3 6.3 ± 1.2 155 ± 33
0.32 41 ± 3.7 30.0c
6.5 ± 0.84 6.2 ± 1.2 4.5 ± 0.6 205 ± 15
1.25 63 ± 27 39 ± 8.9 18 ± 7.9 9 ± 3.5 5 ± 1.7 238 ± 10
5 74 ± 4.1 44 ± 2.9 24 ± 0.5 11 ± 1.8 5 ± 1.2 361 ± 23
a
SE, standard error.
b
Vehicle control.
c
n = 1 animal.
n = 3 animals/sex/dose level (prolactin measurements were conducted in samples from 3 animals/sex/dose level).

levels were not affected as shown in Table 5, a treatment-related
effect could not be excluded. There were no mammary changes
in the males.
The mean toxicokinetic parameters are summarized in Table 6.
After single and repeated dose administration, the AUC values of
JNJ-37822681 generally increased dose proportionally.
Experiment 3. Three-month repeat dose toxicity study with a
1-month recovery phase in monkeys
Initially the animals were dosed at 0.1, 0.3 and 1 mg eq. kg–1
day–
1
for 14 days. While no clinical signs were noted at 0.1 mg eq. kg–
1
day–1
, the animals showed reduced activity and hunched
posture at 0.3 and 1 mg eq. kg–1
day–1
. As adaptation occurred,
the dose levels were increased on day 14 to 0.16, 0.63 and
2.5 mg eq. kg–1
day–1
. No clinical signs were noted at 0.16 mg eq.
kg–1
day–1
. Hypoactivity was observed at 0.63 and 2.5 mg eq. kg–
1
day–1
. Again, the clinical signs lessened during the course of
treatment. Therefore, the dose levels were increased to 2.5, 5
day–1
on day 29. Hypoactivity was found at
2.5 and 5 mg eq. kg–1
day–1
, and tremors at 5 and 10 mg eq.
kg–1
day–1
day–1
, excessive drowsiness was
noted, which was apparent even 24 h after dosing. Therefore,
dosing at 10 mg eq. kg–1
day–1
was suspended for 2 days (days
59 and 60 of the study). Thereafter the hypoactivity was less se-
vere for some days, but then reappeared. Moreover, animals
dosed at 10 mg eq. kg–1
day–1
also displayed hunched posture,
tremors, emesis, salivation, a lying position and occasional dis-
charge of the mammary papillary. Subsequently, the high dose
level was reduced to 7.5 mg eq. kg–1
day–1
on day 71 and
remained unchanged for the remainder of the study until day
91. The low- and mid-dose levels remained unchanged at 2.5
and 5 mg eq. kg–1
day–1
, respectively. At 5 mg eq. kg–1
day–1
,
salivation and occasional discharge of the mammary papillary
were noted, while at 7.5 mgeq. kg–1
day–1
the animals were
hypoactive, showed hunched posture, tremors, emesis, salivation,
a lying position and occasional discharge. The behavioral changes
were dose- and time-related, and generally were reversible.
Serum prolactin levels were increased at 2.5 to 10 mgeq. kg–
1
day–1
as shown in Table 7. There was no clear dose–response re-
lationship. Generally, the hyperprolactinemia was apparent at 1 to
4 or 8 h postdose both on days 37 and 78 of the study. At 24h
postdose, the serum prolactin levels returned to baseline. At the
end of the recovery phase, the prolactin levels were normal.
At necropsy one high-dose female showed bilateral discharge
of the mammary gland. Microscopic examination of the female
mammary gland (Table 8) demonstrated ectasia of the ducts
and hypertrophy of the acinar epithelium with formation of
secretion in some animals of different dose groups, including
control animals. Although the activity of the mammary glands
with formation of secretion varied due to the normal estrous
cycle, and although the effect was seen in control animals
(graded minimal), a minor increase in two females dosed at
2.5 mg eq. kg–1
day–1
and two females at 5 mg eq. kg–1
day–1
was observed. These animals also showed epithelial vacuolation
of the acini. No mammary changes versus control were noted
in females dosed at 7.5 mg eq. kg–1
day–1
or in males.
Histopathology ﬁndings seen after the recovery period were
similar in control and dosed animals.
Toxicokinetic analysis generally revealed a dose-proportional
increase of exposure to JNJ-37822681. The mean toxicokinetic
parameters are summarized in Table 9.
Experiment 4. Nine-month repeat dose toxicity study in monkeys
Initially the animals were dosed at 0.1, 0.3 and 1 mgeq. kg–1
day–1
.
During the course of treatment, these doses were gradually
Table 6. Mean toxicokinetic parameters (± SDa
) of JNJ-37822681 in the 1-month repeat dose toxicity study in cynomolgus
monkeys
Single dose
Dose level (mg eq.kg–1
) 0.63 1.25 2.5 5 10 20
Day of plasma sampling 8 1 8 1 8 1
Males
Cmax (ng ml–1
) 71.6 ± 28.9 99.1 ± 26.1 271 ± 124 388 ± 88.7 1040 ± 210 1573 ± 382
AUC0-∞ (ng h–1
ml–1
) 362 ± 199 586 ± 259 1968 ± 37.5 3288 ± 331 10512 ± 1229 19066 ± 2477
Females
Cmax (ng ml–1
) 89.8 ± 18.8 118 ± 38.7 279 ± 167 461 ± 39.7 1009 ± 246 1310 ± 145
AUC0-∞ (ng h–1
ml–1
) 564 ± 164 824 ± 180 2474 ± 1282 4607 ± 1777 8321 ± 1751 15277 ± 2113
Repeated dosing
day–1
) 0.32 1.25 5
Day of sampling 42 42 42
Males
Cmax (ng ml–1
) 49.3 ± 0.57 178 ± 29.0 664 ± 311
AUC0–24 h (ng h–1
ml–1
) 274 ± 52.7 926 ± 60.2 4583 ± 1371
Females
Cmax (ng ml–1
) 46.6 ± 9.77 185 ± 53.5 614 ± 74.4
ml–1
) 298 ± 100 1329 ± 647 4720 ± 711
a
SD, standard deviation.
n = 3 animals/sex/dose level.

Table7.Meanserumprolactinlevels(±SDa
)inthe3-monthrepeatdosetoxicitystudyincynomolgusmonkeys
Doselevel
(mgeq.kg–1
day–1
)
0hpostdose
(mUl–1
)
1hpostdose
(mUl–1
)
2hpostdose
(mUl–1
)
4hpostdose
(mUl–1
)
8hpostdose
(mUl–1
)
24hpostdose
(mUl–1
)
AUC0–24h
(mUh–1
l–1
)
Males,day37
0b
87±16(n=5)61±18(n=5)58±15(n=5)43±8(n=5)58±11(n=5)84±156(n=5)1574±273(n=5)
2.5134±45(n=3)1466±107(n=3)679±170(n=3)354±66(n=3)200±110(n=3)108±16(n=3)6479±1701(n=3)
5138±39(n=3)1697±481(n=3)938±111(n=3)556±82(n=3)324±68(n=3)128±60(n=3)9107±1998(n=3)
10122±117(n=5)1978±802(n=5)1054±413(n=5)690±329(n=5)473±302(n=5)185±283(n=5)11901±7415(n=5)
Females,day37
0168±91(n=5)127±73(n=5)123±76(n=5)120±60(n=5)139±68(n=5)146±63(n=5)3313±1542(n=5)
2.5196±80(n=3)3061±1191(n=3)1483±306(n=3)801±179(n=3)358±211(n=3)150±26(n=3)12570±4432(n=3)
5284±84(n=3)5163±621(n=3)2173±740(n=3)1421±453(n=3)1054±113(n=3)237±158(n=3)25271±5425(n=3)
10158±145(n=5)3176±1232(n=5)1425±534(n=5)952±386(n=5)643±321(n=5)121±94(n=5)15664±7009(n=5)
Males,day78
093±35(n=5)91±23(n=5)66±18(n=5)67±15(n=5)69±20(n=5)90±35(n=5)1851±542(n=5)
2.573±14(n=3)1424±198(n=3)645±172(n=3)309±88(n=3)192±98(n=3)106±31(n=3)6128±1918(n=3)
570±28(n=3)1863±453(n=3)1049±194(n=3)486±90(n=3)322±76(n=3)104±32(n=3)8978±1866(n=3)
7.555±40(n=5)2462±1052(n=5)988±418(n=5)605±387(n=5)310±241(n=5)47±32(n=5)9267±5453(n=5)
Females,day78
091±32(n=5)106±37(n=5)77±30(n=5)64±23(n=5)154±46(n=5)130±34(n=5)3036±810(n=5)
2.5118±41(n=3)4760±1881(n=3)1872±624(n=3)898±389(n=3)441±228(n=3)176±49(n=3)16137±6423(n=3)
5153±76(n=3)6135±1900(n=3)2278±598(n=3)1330±261(n=3)922±63(n=3)194±122(n=3)24391±3051(n=3)
7.5145±127(n=4)5142±2706(n=4)1871±751(n=4)998±373(n=4)723±391(n=3)154±119(n=3)21238±8921(n=3)
a
SD,standarddeviation.
b
Vehiclecontrol.

escalated to 0.3, 0.75 and 2.5 mgeq. kg–1
day–1
and subsequently
0.6, 1.5 and 5 mg eq. kg–1
day–1
(Table 3).
Clinical signs observed for the high-dose animals (1.0/2.5/5mg
eq. kg–1
day–1
) predominantly included hypoactivity, trance-like
state, body tremors, piloerection, salivation, repetitive movements,
and abnormal eye movements described as “tracking of invisible
objects.” There was considerable interindividual variation in the se-
verity and duration of the signs with male animals tending to show
a more marked response than females. At 1.0 mgeq. kg–1
day–1
,
clinical observations included slight hypoactivity, body tremors
and piloerection. One animal showed a slight trance-like state on
day 2, from 2 to 4 h postdose until the end of the day.
On day 15, the high dose level was escalated from 1 to 2.5 mg
eq. kg–1
day–1
. From that point in time onwards all males
showed a slight trance-like state at 1–2 h postdose until the
end of the working day, but did not show this behavior by the
following morning. At this dose level, females began to present
with slight body tremors and some hypoactivity, but with a
lower incidence and shorter duration than the males.
On day 43, the high dose level was escalated further to 5 mg eq.
kg–1
day–1
. Further to previous observations, at this dose level,
female animals intermittently presented with a slight/moderate
trance-like state between 1 and 2 h postdose and at the end of
the day. The incidence and severity of hypoactivity and body
tremors for both sexes and piloerection for females increased fol-
lowing this last dose escalation, with the majority of animals
presenting these signs from dosing until the following morning
predose observation. Novel observations at 5 mgeq. kg–1
day–1
in-
cluded apparent “tracking of invisible objects” (recorded as slight
in terms of severity). This behavior was ﬁrst observed in one male
animal on day 70, but progressed to an intermittent observation
seen for males and females from week 20 onwards until the end
of the study, and slight to moderate repetitive movements, which
were observed for a few animals from weeks 16 to 32. Both signs
were generally evident at the peak effect time of 1–2 h after
dosing until the end of the working day. Salivation was noted
during and immediately after dosing.
In the intermediate dose group (0.3/0.75/1.5mg eq. kg–1
day–1
)
the clinical signs predominantly included piloerection, hypoactivity,
body tremors and a trance-like state. At 0.3mgeq. kg–1
day–1
, a few
Table 8. Mammary gland histopathology ﬁndings in the 3-
Dose level
(mg eq. kg–1
day–1
)
0a
2.5 5 7.5
Males
3 3 3 3
Ectasia of ducts 1 0 1 0
Females
3 3 3 3
Ectasia of ducts 1 2 1 1
Epithelial vacuolation 0 2 2 0
Hypertrophy 1 3 2 1
a
Vehicle control.
Table9.Meantoxicokineticparameters(±SDa
)ofJNJ-37822681inthe3-monthrepeatdosetoxicitystudyincynomolgusmonkeys
Doselevel(mgeq.kg–1
day–1
)0.10.160.30.6312.557.510
Dayofplasmasampling13141314131491919170
Males
Cmax(ngml–1
)7.61±1.6611.5±5.0018.8±5.7854.4±9.1182.8±12.4265±43.7317±75.5680±120673±68.3773±108
AUC0–24h(ngh–1
ml–1
)24.0±13.080.2±21.9106±29.4423±158407±1062071±5462163±4905798±9526518±12268184±1740
Females
Cmax(ngml–1
)5.52±0.52510.0±2.7918.8±3.2741.5±2.7285.5±21.0283±82.1293±108602±206861±169969±161
AUC0–24h(ngh–1
ml–1
)20.9±11.855.6±8.3794.8±8.56384±8.79411±67.32189±21892092±4175354±8098613±117610165±2418
a
SD,standarddeviation.
n=3animals/sex/doselevelat0.1(days1–13)/0.16(days14–28)/2.5(days29–91)mgeq.kg–1
day–1
n=3animals/sex/doselevelat0.3(days1–13)/0.63(days14–28)/5(days29–91)mgeq.kg–1
day–1
n=5animals/sex/doselevelat1(days1–13)/2.5(days14–28)/10(days29–70)/7.5(days71–91)mgeq.kg–1
day–1

animals showed slight piloerection and loose/liquid feces. Following
dose escalation to 0.75mgeq. kg–1
day–1
on day 15 slight body
tremors were observed in one male, and occasionally slight body
tremors and hypoactivity in two females. On day 43, the dose level
was escalated further to 1.5 mg eq. kg–1
day–1
. This resulted in
an increase in the incidence of hypoactivity and body tremors.
A slight trance-like state was noted in all males and two females
starting at 1–2 h postdose and lasting to the end of the working
day. One animal occasionally displayed apparent “tracking of
invisible objects”.
In the low-dose group (0.1/0.3/0.6 mg eq. kg–1
day–1
) some
loose/liquid feces and slight to moderate piloerection
were observed at each of the dose escalations. Following
dose escalation to 0.6mgeq. kg–1
day–1
on day 43 infrequently
slight hypoactivity and body tremors were seen. One
animal dosed at 0.6mgeq. kg–1
day–1
occasionally showed a
trance-like state.
At weeks 26 and 39 serum prolactin were elevated at 2 and 4 h
postdose and declined to predose levels by 8 or 24 h postdose.
There was no clear dose–response relationship. In general, the
prolactin increase was more pronounced in females than in male
animals. The mean serum prolactin levels are summarized in
Table 10. This hyperprolactinemia did not result in any tissue
changes. In fact, the macroscopic and microscopic pathology
examinations did not reveal treatment-related effects in any tissue.
Toxicokinetic analyses on days 50 and 272 showed that the
mean plasma Cmax and AUC values of JNJ-37822681 generally
increased dose proportionally. No sex differences were noted.
Table 10. Mean serum prolactin levels (± SDa
) in the 9-month repeat dose toxicity study in cynomolgus monkeys
Dose level
(mg eq. kg–1
day–1
)
Predose
(ng ml–1
)
2 h postdose
(ng ml–1
)
4 h postdose
(ng ml–1
)
8 h postdose
(ng ml–1
)
24 h postdose
(ng ml–1
)
Males, week 26
0b
5.96 ± 1.70 (nc
= 2) 3.80 ± 1.72 (n = 4) 4.35 ± 2.62 (n = 3) 3.74 ± 2.16 (n = 2) 5.33 ± 2.38 (n = 2)
0.6 12.1 (n = 1) 28.2 ± 12.1 (n = 4) 11.2 ± 3.6 (n = 4) 5.09 ± 3.24 (n = 3) 7.59 ± 7.52 (n = 2)
1.5 3.49 ± 0.45 (n = 3) 71.8 ± 46.1 (n = 3) 21.5 ± 12.1 (n = 3) 5.70 ± 2.58 (n = 3) 3.48 ± 0.11 (n = 3)
5 3.76 (n = 1) 45.8 ± 19.2 (n = 4) 17.4 ± 9.2 (n = 4) 5.68 ± 3.58 (n = 4) 2.95 ± 0.91 (n = 3)
Females, week 26
0 9.49 ± 7.36 (n = 4) 5.64 ± 2.35 (n = 4) 8.42 ± 2.43 (n = 4) 7.45 ± 2.62 (n = 4) 6.90 ± 4.09 (n = 4)
0.6 5.38 ± 0.85 (n = 3) 95.5 ± 47.7 (n = 4) 21.5 ± 11.1 (n = 4) 7.55 ± 4.51 (n = 4) 5.79 ± 0.47 (n = 3)
1.5 5.01 ± 2.86 (n = 3) 71.9 ± 22.0 (n = 4) 20.8 ± 7.8 (n = 4) 6.00 ± 2.71 (n = 4) 4.67 ± 3.16 (n = 4)
5 4.04 ± 2.39 (n = 4) 96.7 ± 23.9 (n = 4) 38.7 ± 12.6 (n = 4) 12.0 ± 6.1 (n = 4) 4.37 ± 0.71 (n = 3)
Males, week 39
0 4.47 ± 2.88 (n = 4) 6.52 ± 5.36 (n = 3) 6.38 ± 5.13 (n = 4) 5.56 ± 1.80 (n = 3) 3.86 ± 2.32 (n = 3)
0.6 3.31 ± 1.77 (n = 4) 49.0 ± 38.2 (n = 4) 16.1 ± 11.5 (n = 4) 4.19 ± 1.45 (n = 3) 4.68 ± 1.74 (n = 2)
1.5 4.82 ± 1.90 (n = 3) 55.0 ± 32.0 (n = 3) 16.7 ± 10.2 (n = 3) 6.84 ± 3.19 (n = 3) 4.32 ± 2.06 (n = 3)
5 3.13 ± 1.06 (n = 3) 40.7 ± 18.2 (n = 4) 15.4 ± 9.0 (n = 4) 5.20 ± 2.52 (n = 4) 3.10 ± 1.00 (n = 2)
Females, week 39
0 7.24 ± 2.28 (n = 3) 9.14 ± 5.45 (n = 4) 5.98 ± 1.73 (n = 4) 5.27 ± 1.05 (n = 3) 7.31 ± 3.74 (n = 3)
0.6 4.07 ± 1.77 (n = 3) 80.3 ± 23.1 (n = 4) 17.8 ± 7.6 (n = 4) 4.96 ± 2.41 (n = 4) 4.00 ± 1.41 (n = 3)
1.5 4.80 ± 1.84 (n = 4) 132 ± 96 (n = 4) 33.8 ± 22.6 (n = 4) 8.14 ± 4.85 (n = 4) 5.33 ± 2.04 (n = 4)
5 4.19 ± 2.10 (n = 4) 80.4 ± 24.3 (n = 4) 28.8 ± 4.3 (n = 4) 9.15 ± 2.48 (n = 4) 3.73 ± 1.45 (n = 4)
a
b
Vehicle control.
c
n, number of animals.
) of JNJ-
37822681 in the 9-month repeat dose toxicity study in
cynomolgus monkeys
Dose level
(mg eq. kg–1
day–1
)
0.6 1.5 5
Males, day 50
Cmax (ng ml–1
) 63.6 ± 22.2 207 ± 38.7 748 ± 255
AUC0–24 h
(ng h–1
ml–1
)
518 ± 111 1868 ± 684 6074 ± 2693
Females, day 50
Cmax (ng ml–1
) 89.3 ± 3.48 188 ± 54.6 684 ± 296
AUC0–24 h
(ng h–1
ml–1
)
619 ± 74.5 1508 ± 498 5508 ± 1301
Males, day 272
Cmax (ng ml–1
) 79.5 ± 19.4 303 ± 37.7b
877 ± 144
AUC0–24 h
(ng h–1
ml–1
)
685 ± 225 2173 ± 274b
7396 ± 1535
Females, day 272
Cmax (ng ml–1
) 90.8 ± 24.7 244 ± 80.5 614 ± 89.6
AUC0–24 h
(ng h–1
ml–1
)
644 ± 138 1821 ± 663 5396 ± 715
a
b
n = 3 animals.

Mean Tmax was established at 0.5–4 h postdose. The mean
toxicokinetic parameters are summarized in Table 11.
Studies in Sprague–Dawley rats
Experiment 5. Tolerability study in rats
During the single dose phase the animals dosed at 20 or 40 mg
kg–1
showed no treatment-related changes. At 80 mg kg–1
,
slightly to moderately decreased general activity and narrowing
of the palpebral fissure were observed. During the repeat dose
phase, no remarkable changes were noted at 20 and 80 mg
kg–1 day–1
. After the fifth dose administration at 20 or 80 mg
kg–1 day–1
the mean Cmax values of JNJ-37822681 were 257
and 1130 ng ml–1
, while the mean AUC0–24 h values were 1340
and 9980 ng h–1
ml–1
, respectively.
Experiment 6. One-month repeat dose toxicity study with a
1-month recovery phase in rats
At 20 and 80mgeq. kg–1
day–1
, decreased general activity, narrowing
of the palpebral fissure and hypotonia were observed. On day 1 of
treatment, female rats dosed at 80mgeq. kg–1
day–1
showed
tremors, ataxia and waste of food. There were no treatment-related
clinical observations during the 1-month recovery phase.
Serum prolactin levels were slightly or moderately increased
in male rats dosed at 20 or 80 mg eq. kg–1
day–1
, and in females
at all dose levels (Table 12). This hyperprolactinemia generally
was apparent at 2–6 h postdose on days 0 and 21 of the study.
The prolactin levels returned to baseline at 24 h postdose. At
the end of recovery, the prolactin AUC values had returned to
baseline in males. Three of five females still showed increased
prolactin levels, which might be related to a peak of pro-estrus.
However, an effect of previous treatment with JNJ-37822681
could not be ruled out.
Prolactin-mediated tissue changes were evident at all dose
levels, and included increased tubulo-alveolar development of
the male mammary glands, increased glandular development
with prominent secretion in the female mammary gland
(Table 13), reduced cyclic activity with a tendency towards
prolonged diestrus and pseudopregnancy in the female genital
tract, and inflammation of the dorsolateral prostate. The adeno-
hypophysis showed an increase in prolactin immune-positive
cells in both sexes. The severity of these findings generally
increased with dose. In addition, a low epithelium of the coagu-
lating glands and seminal vesicles was found in males treated at
80 mg eq. kg–1
day–1
, and focal hyperplasia of the mammary
glands in two of 10 female rats at 80 mg eq. kg–1
day–1
. At the
end of recovery, the female mammary gland and prostate were
almost normal; all other tissues showed complete recovery.
Toxicokinetic analysis showed that the AUC values of the
parent compound increased dose-proportionally from 5 to
80 mg eq. kg–1
day–1
. The exposures were higher in females
than in males. The mean toxicokinetic parameters are summarized
in Table 14.
) in the 1-month repeat dose toxicity study in Sprague–Dawley rats
Dose level
(mg eq. kg–1
day–1
)
Predose
(ng ml–1
)
2 h postdose
(ng ml–1
)
4 h postdose
(ng ml–1
)
6 h postdose
(ng ml–1
)
24 h postdose
(ng ml–1
)
Mean AUC0–24h
value (ng h–1
ml–1
)
Males, day 0
0b
13.85 ± 1.66 6.71 ± 1.04 14.98 ± 1.87 10.21 ± 0.92 10.57 ± 2.34 254 ± 30
5 11.88 ± 1.90 17.20 ± 1.68*** 17.78 ± 3.62 12.83 ± 5.82 11.98 ± 5.48 318 ± 113
20 13.57 ± 2.53 22.44 ± 2.28*** 21.41 ± 1.64* 14.30 ± 2.77 6.61 ± 1.11 304 ± 29
80 7.47 ± 0.74** 27.32 ± 2.11*** 24.13 ± 1.95** 22.91 ± 1.96*** 3.08 ± 0.06*** 360 ± 24*
Females, day 0
0 26.62 ± 10.15 20.78 ± 11.76 76.32 ± 49.71 40.72 ± 10.38 17.47 ± 6.09 785 ± 176
5 14.85 ± 9.59 231.54 ± 44.91*** 186.01 ± 43.75*** 323.33 ± 63.33*** 40.45 ± 26.77 4411 ± 651***
20 15.13 ± 5.11 298.26 ± 24.92*** 188.51 ± 20.41*** 248.49 ± 28.73*** 11.14 ± 5.71 3574 ± 319***
80 26.08 ± 7.86 294.59 ± 21.66*** 206.41 ± 21.27*** 216.59 ± 21.89*** 413.58 ± 67.15*** 6916 ± 677***
Males, day 21
0 27.50 ± 4.60 34.60 ± 3.93 20.51 ± 3.22 7.10 ± 1.08 27.15 ± 3.44 453 ± 44
5 33.95 ± 5.49 71.84 ± 10.00*** 20.67 ± 5.53 13.07 ± 4.58 19.43 ± 2.85 525 ± 69
20 21.65 ± 5.62 107.30 ± 14.69*** 63.03 ± 7.25*** 68.45 ± 12.14*** 15.98 ± 4.11 1191 ± 164***
80 3.87 ± 0.42*** 129.80 ± 10.77*** 80.12 ± 10.93*** 96.90 ± 10.51*** 4.16 ± 0.85*** 1430 ± 136***
Females, day 21
0 40.18 ± 12.16 30.04 ± 7.73 50.97 ± 18.18 133.70 ± 35.91 98.49 ± 49.46 2426 ± 647
5 7.34 ± 3.59*** 342.44 ± 30.94*** 210.16 ± 19.59*** 337.98 ± 81.49** 18.49 ± 9.54 4659 ± 848*
20 3.68 ± 0.55*** 416.78 ± 51.28*** 259.18 ± 27.53*** 302.57 ± 39.31** 10.50 ± 6.23* 4476 ± 374**
80 43.33 ± 19.79* 462.36 ± 69.69*** 331.47 ± 51.36*** 282.77 ± 31.70** 14.11 ± 6.31* 4586 ± 524**
a
SE, standard error.
b
Vehicle control.
Animal number: n = 15/sex in the vehicle control and 80 mg eq. kg–1
day–1
-dosed groups; n = 10/sex in the 5 and 20 mg eq. kg–
1
day–1
-dosed groups.
Significance versus vehicle control computed by Mann–Whitney U test (two-tailed):
* P < 0.05; ** P < 0.01; *** P < 0.001.

Microscopic examination indicated near to complete recovery
of the changes in the prostate and female mammary gland.
Experiment 7. Three-month repeat dose toxicity study in rats
Rats dosed at 10 or 40 mg eq. kg–1
day–1
showed slightly
decreased general activity and narrowing of the palpebral
fissure. In male rats, the serum prolactin AUC levels were slightly
increased at 10 and 40 mg eq. kg–1
day–1
. Females showed a
slight to moderate increase in prolactin levels at all dose levels
(Table 15). This hyperprolactinemia was generally apparent at 2
to 6 h postdose on day 21 and 84 of the study. The prolactin
levels returned to baseline at 24 h postdose.
At 2.5 mg eq. kg–1
day–1
prolonged diestrus and pseudopreg-
nancy were noted in the female genital tract. The mammary
histopathology findings are summarized in Table 16. The female
mammary gland showed minimal glandular development with
secretion. At 10 mg eq. kg–1
day–1
, these changes were more
pronounced. The male mammary gland showed a female
appearance characterized by a tubulo-alveolar pattern. At 40 mg
eq. kg–1
day–1
, the genital tract and mammary gland changes
were even more prominent. At that dose level, the dorsolateral
prostate showed an increase in granulocyte infiltration. One
female dosed at 2.5 mg eq. kg–1
day–1
displayed a mammary
gland adenoma.
Toxicokinetic analysis showed that the AUC values of the
parent compound increased dose-proportionally across dose
levels. The exposures were higher in females than in males.
The mean toxicokinetic parameters are summarized in Table 17.
Experiment 8. Six-month repeat dose toxicity study in rats
The JNJ-37822681-treated rats showed a dose-related underac-
tivity until 6 h postdose. This sign was not apparent anymore
the following morning. At 10 mg eq. kg–1
day–1
the females were
overactive in the morning, before dosing and on return to the
cage after dosing at weeks 8, 12 and 20; males were overactive
in week 12 only. At 40 mg eq. kg–1
day–1
, closure of the palpebral
fissure and occasionally piloerection were noted and, from
weeks 8 to 20, the animals were overactive in the morning,
before dosing, and on return to the cage after dosing.
Serum prolactin levels were slightly to moderately increased in
males at 10 and 40mgeq. kg–1
day–1
. In females, there was a slight
to moderate increase in serum prolactin levels at all dose levels
without a clear dose–response relationship (Table 18). This
hyperprolactinemia was generally apparent at 2–6 h postdose on
days 52 and 136 of the study. The prolactin levels returned to base-
line at 24 h postdose.
There was a dose-related tendency towards pseudopregnancy
in females at all dose levels. In the female mammary gland, a
dose-related increase in glandular development and secretion
was observed. Focal fibro-adenosis was seen in two of 19 females
at 10 mgeq. kg–1
day–1
and one of 19 female rats at 40 mg eq.
kg–1
day–1
. The male mammary gland showed a female appear-
ance characterized by tubulo-alveolar development at 40 mg eq.
kg–1
day–1
. The mammary histopathology findings are summa-
rized in Table 19. Inflammation of the dorsolateral prostate was
seen in a few males dosed at 40 mgeq. kg–1
day–1
. Mainly in
females, the sublingual and mandibular salivary glands showed a
decrease in mucin content at 40 mgeq. kg–1
day–1
.
Toxicokinetic analysis revealed that the AUC values of the
parent compound increased more than dose-proportionally in
males, and less than dose-proportionally in females. The expo-
sures were higher in females compared to males (Table 20).
Discussion
The rat is a rodent species commonly used in regulatory toxicology
studies with small molecule pharmaceuticals such as JNJ-
37822681, while the dog generally is the preferred non-rodent
species. However, the dog was prone to emesis upon dosing of
JNJ-37822681 and consequently showed low oral bioavailability.
The minipig was not suitable either because that species also
showed low exposures. The cynomolgus monkey was eventually
selected because in this species considerably higher exposures
month repeat dose toxicity study in Sprague–Dawley rats
Dose level
(mg eq. kg–1
day–1
)
0a
5 20 80
Males
10 10 10 10
Number of animal affected
Female
aspect
Minimal 0 2 4 5
Slight 0 0 2 5
Prominent
secretion
Minimal 0 0 0 1
Females
10 10 9 10
Glandular
development
Minimal 6 3 3 1
Slight 0 6 6 4
Moderate 0 0 0 5
Prominent
secretion
Minimal 0 2 3 1
Slight 0 0 2 7
Moderate 0 0 0 2
Focal
hyperplasia
Slight 0 0 0 2
a
Vehicle control.
Table 14. Mean toxicokinetic parameters of JNJ-37822681
in the 1-month repeat dose toxicity study in Sprague–Dawley
rats
day–1
) 5 20 80
Males, day 27
Cmax (ng h–1
ml–1
) 169 357 1020
ml–1
) 382 1580 6730
Females, day 27
Cmax (ng h–1
ml–1
) 289 712 1450
ml–1
) 1300 4900 12 400

Dose level
(mg eq. kg–1
day–1
)
Predose
(ng ml–1
)
2 h postdose
(ng ml–1
)
4 h postdose
(ng ml–1
)
6 h postdose
(ng ml–1
)
24 h postdose
(ng ml–1
)
Mean AUC0–24h
value (ng h–1
ml–1
)
Males, day 21
0b
10.81 ± 2.55 11.92 ± 3.09 22.33 ± 6.57 14.99 ± 2.67 34.16 ± 5.83 537 ± 93
2.5 24.94 ± 4.21* 52.26 ± 5.73*** 30.91 ± 4.91 26.17 ± 4.06* 32.44 ± 7.02 745 ± 97
10 28.69 ± 5.10** 81.53 ± 8.43*** 43.25 ± 4.39** 34.92 ± 4.44** 34.25 ± 8.98 936 ± 101**
40 15.18 ± 4.21 136.37 ± 13.05*** 80.07 ± 8.13*** 51.89 ± 5.77*** 7.28 ± 1.01*** 1032 ± 91***
Females, day 21
0 24.96 ± 6.81 11.23 ± 3.04 93.06 ± 42.36 40.64 ± 11.34 56.35 ± 40.23 1147 ± 420
2.5 19.66 ± 12.62* 285.43 ± 67.11*** 350.45 ± 154.98 156.67 ± 78.82 26.61 ± 16.85 3098 ± 1,376
10 6.06 ± 2.58** 319.44 ± 35.72*** 325.36 ± 57.61** 433.29 ± 79.41*** 6.73 ± 1.91* 5689 ± 928***
40 18.57 ± 8.54 475.75 ± 44.75*** 276.44 ± 25.00** 483.70 ± 73.74*** 15.65 ± 7.41 6502 ± 800***
Males, day 84
0 25.85 ± 6.45 25.05 ± 10.61 25.97 ± 9.31 23.48 ± 3.64 20.30 ± 5.39 556 ± 122
2.5 15.67 ± 3.59 38.68 ± 5.97* 14.65 ± 4.19 12.18 ± 1.93** 26.51 ± 4.51 483 ± 67
10 16.40 ± 3.82 101.95 ± 17.33*** 37.12 ± 6.70 34.74 ± 8.22 31.77 ± 8.79 928 ± 146*
40 5.60 ± 1.67*** 229.95 ± 37.85*** 86.84 ± 9.91*** 79.97 ± 9.45*** 4.77 ± 1.08*** 1482 ± 180***
Females, day 84
0 63.12 ± 26.92 36.02 ± 11.60 37.70 ± 8.56 415.54 ± 99.07 224.49 ± 65.88 6386 ± 1180
2.5 138.39 ± 77.72 853.54 ± 160.08*** 265.57 ± 63.50*** 463.56 ± 184.54 24.35 ± 12.24*** 7231 ± 2289
10 7.21 ± 2.37** 854.93 ± 115.68*** 560.47 ± 51.99*** 776.12 ± 73.90** 28.49 ± 12 10 856 ± 793**
4.33**
40 6.27 ± 1.69* 799.85 ± 142.93** 439.94 ± 62.53** 481.51 ± 102.71 12.19 ± 4.30*** 7411 ± 1392
a
SE, standard error.
b
Vehicle control.
n = 10 animals/sex/group.
* P < 0.05; ** P < 0.01; *** P < 0.001.
month repeat dose toxicity study in Sprague–Dawley rats
Dose level
(mg eq. kg–1
day–1
)
0a
2.5 10 40
Males
9 10 10 10
Female aspect Minimal 0 1 6 2
Slight 0 0 4 8
Females
10 10 10 10
Glandular
development
Minimal 4 6 0 1
Slight 0 4 10 7
Moderate 0 0 0 2
Secretion Minimal 0 3 5 8
Slight 0 0 0 1
Adenoma 0 1 0 0
a
Vehicle control.
) of JNJ-
37822681 in the 3-month repeat dose toxicity study in
Sprague–Dawley rats
Dose level
(mg eq. kg–1
day–1
)
2.5 10 40
Males, day 27
Cmax (ng h–1
ml–1
) 50.2 236 483
ml–1
) 197 663a
2460
Females, day 27
Cmax (ng h–1
ml–1
) 153 341 927
ml–1
) 536 2340 6790
Males, day 91
Cmax (ng h–1
ml–1
) 85.8 215 387
ml–1
) 196 777 2740
Females, day 91
Cmax (ng h–1
ml–1
) 141 393 813
ml–1
) 533 1830 6200
a
AUC0-7 h value.

of parent drug could be achieved, while its in vivo metabolic
proﬁle of JNJ-37822681 adequately resembled that in humans.
In the monkey tolerability study, late prepubertal to adult ani-
mals 2.5–8 years of age were used. JNJ-37822681 was reasonably
well tolerated at 20 mgkg–1 day–1
for 5 consecutive days. This out-
come guided the selection of the 1.25, 5 and 20 mg eq. kg–1
day–1
dose levels of JNJ-37822681 for the subsequent 1-month repeat
dose monkey study. However, unexpectedly these dose levels
induced prolonged excessive sleepiness even after a single admin-
istration. These dose levels were therefore considered too high.
When the study restarted at 0.63, 2.5 and 10 mg eq. kg–1
again
excessive sleepiness was observed at all dose levels. Only in the
third instance, when the dose levels were further reduced to
0.16, 0.63 and 2.5mg eq. kg–1
day–1
, treatment could successfully
be maintained over 14 consecutive days. Adaption allowed the
dose levels to be increased to 0.32, 1.25 and 5 for the remainder
of the study. The dose of 0.16 mgeq. kg–1
day–1
was considered
the no-observed-effect level, whereas the no-observed-adverse
effect level (NOAEL) was estimated to be 0.32 mg eq. kg–1
day–1
.
At the latter dose level, two of six animals were subdued and
showed hunched posture on day 42 of the study, i.e., following
approximately 14 days of treatment; on the other treatment days,
none of the animals treated at 0.32 mgeq. kg–1
day–1
showed
clinical signs. These effects were considered incidental and not
adverse for an antipsychotic compound.
Retrospectively, the erroneous dose selection in the 1-month
monkey study most probably was because animals of early
prepubertal or juvenile age were used (i.e., approximately
1.5–2 years old at the start of dosing). These animals apparently
were more sensitive to JNJ-37822681-induced clinical signs than
the older ones used in the tolerability study. The dose escalation
in the 1-month study, however, proved to be a successful strat-
egy to, nevertheless, achieve reasonably high exposures.
To avoid similar issues the animals in the 3- and 9-month mon-
key studies were initially treated at relatively low dose levels. After
adaptation, the dose levels were gradually increased during the
course of treatment. Accordingly, in the 3-month monkey study
the dose levels were gradually increased from 0.1, 0.3 and 1 mg eq.
kg–1
day–1
to a maximum 2.5, 5 and 10 mg eq. kg–1
day–1
on days
29–70. However, the 10 mg eq. kg–1
day–1
dose level could not
be maintained due to re-occurring excessive drowsiness. Conse-
quently, it was reduced to 7.5mgeq. kg–1
day–1
towards termina-
tion. In contrast, the degree of sedation in JNJ-37822681-treated
rats was only mild and transient, and therefore had no impact on
dose selection. Monkeys dosed at 2.5mg eq. kg–1
day–1
in the 3-
month study only displayed slight hypoactivity. This dose level
was therefore considered the NOAEL in that study, and was asso-
ciated with AUC0–24 h values of 2163 and 2092ngh–1
ml–1
in male
and female monkeys, respectively. In the 9-month monkey study,
dose titration allowed maximum dose levels of 0.6, 1.5 and 5 mg
eq. kg–1
day–1
from day 43 towards termination. The animals
receiving 0.6mg eq. kg–1
day–1
displayed very few clinical signs
when compared to those dosed at 1.5 or 5 mg eq. kg–1
day–1
.
However, based on similar observations in the previous monkey
studies these signs were considered associated with treatment
and included hypoactivity, a trance-like state indicative of EPS on
Dose level
(mg eq. kg–1
day–1
)
0 h postdose
(ng ml–1
)
2 h postdose
(ng ml–1
)
4 h postdose
(ng ml–1
)
6 h postdose
(ng ml–1
)
24 h postdose
(ng ml–1
)
Mean AUC0–24h value
(ng h–1
ml–1
)
Males, day 52
0b
7.8 ± 1.07 4.0 ± 0.48 4.4 ± 0.46 8.5 ± 1.66 10.7 ± 1.14 206 ± 19
2.5 10.4 ± 1.04 17.4 ± 1.63*** 8.7 ± 0.86*** 9.2 ± 1.55 10.7 ± 1.69 250 ± 30
10 9.3 ± 1.93 31.9 ± 3.0*** 19.0 ± 2.52*** 19.0 ± 3.16** 14.6 ± 2.03 432 ± 42***
40 13.9 ± 2.47 59.3 ± 6.08*** 44.3 ± 4.47*** 40.5 ± 4.09*** 12.4 ± 3.49 747 ± 67***
Females, day 52
0 212.1 ± 34.58 64.0 ± 16.22 47.4 ± 12.76 119.9 ± 39.62 29.5 ± 7.19 1899 ± 456
2.5 91.1 ± 30.49 272.4 ± 24.61*** 163.9 ± 24.58** 319.5 ± 59.61* 31.5 ± 14.48 4442 ± 701*
10 111.2 ± 35.77 261.2 ± 28.48*** 156.8 ± 15.42*** 247.4 ± 32.34** 26.8 ± 6.61 3662 ± 443**
40 155.3 ± 29.88 201.3 ± 15.36*** 137.6 ± 9.98*** 187.2 ± 7.12** 53.4 ± 11.28 3185 ± 170**
Males, day 136
0 14.6 ± 3.43 7.2 ± 1.70 5.2 ± 1.07 17.5 ± 1.27 11.7 ± 1.70 320 ± 29
2.5 24.8 ± 3.61* 24.0 ± 2.85*** 15.9 ± 2.44*** 15.0 ± 2.77 21.5 ± 2.49** 449 ± 56
10 20.1 ± 3.29 35.1 ± 4.35*** 23.3 ± 2.54*** 28.7 ± 5.39 22.7 ± 3.63* 628 ± 83***
40 19.9 ± 5.52 68.5 ± 6.64*** 49.2 ± 4.60*** 49.5 ± 4.29*** 19.6 ± 6.35 930 ± 90***
Females, day 136
0 398.2 ± 75.99 113.7 ± 20.82 122.0 ± 17.24 106.6 ± 28.49 135.3 ± 41.19 3153 ± 668
2.5 139.3 ± 33.50** 592.7 ± 137.69*** 366.5 ± 63.54** 316.1 ± 66.43* 114.3 ± 27.10 6246 ± 1224
10 143.8 ± 59.91** 342.2 ± 42.13*** 285.1 ± 46.02*** 359.4 ± 45.06*** 251.3 ± 169.84 7254 ± 2068*
40 350.3 ± 137.62 291.1 ± 48.11** 207.4 ± 24.02** 233.2 ± 21.48** 181.4 ± 59.77 5311 ± 932
a
SE, standard error.
b
Vehicle control.
n = 10 animals/sex/group.
* P < 0.05; ** P < 0.01; *** P < 0.001.

a few occasions in one of eight animals, and body tremors on
several occasions in the majority of animals. Consequently, a
NOAEL could not be established. The 0.6mg eq. kg–1
day–1
dose
level was associated with mean AUC0–24 h values of 685 and
644 ngh–1
ml–1
in male and female monkeys, respectively.
JNJ-37822681 induced complex EPS-like signs in all four
monkey toxicology studies very similar to findings reported for
other antipsychotic drugs (Arnsten et al., 1995; Auclair et al.,
2009; Casey, 1993, 1996; Fukuoka et al., 1997; Kumar et al.,
2003; Peacock & Gerlach, 1999). These signs included parkinson-
ism (rigidity, impaired mobility or bradykinesia, staggered move-
ments and tremors), dystonia (sustained abnormal/unusual
postures such as standing like a statue or being in a trance-like
state) and dyskinesias (shaking, flicking or rolling head, repeti-
tive movements and flickering eyes). In addition JNJ-37822681-
treated monkeys elicited hypoactivity, apathy, hunched posture,
recumbency and inability to hold on to the cage. These motor
disorders were consistent with reports of dyskinesias and loco-
motor depressant changes occurring in monkeys with various
other antipsychotics (Casey, 1996; Fukuoka et al., 1997; Goldstein
& Snyder, 1995; Liebman & Neale, 1980; Peacock & Gerlach,
1999; Porsolt & Jalfre, 1981; Rehm et al., 2007; Varty et al., 2008;
Weiss et al., 1977). Catalepsy-associated behavior in monkeys
reflected by static postures and unusual positions occurring for
prolonged periods of time have been described as well (Auclair
et al., 2009; Kumar et al., 2003). Remarkably, however, JNJ-
37822681 induced EPS-like signs in the monkey studies at low
exposures. This finding was unexpected based on fast dissociat-
ing properties of the compound. These observations also seem
to contradict the low EPS liability of JNJ-37822681 predicted
from rat pharmacology experiments (Langlois et al., 2012).
However, monkeys generally tend to be more sensitive than rats
to the motor side effects of antipsychotics (Auclair et al., 2009). In
the case of JNJ-378722681, a comparison between rats and
monkeys in this respect is hampered by the lack of pharmacol-
ogy data in monkeys. In particular, the margin, if any, between
the antipsychotic activity and the occurrence of EPS-like signs
in monkeys, is unknown. Notably the catalepsy reported at a
single dose of 8 mg kg–1
(subcutaneous ED50 value) in JNJ-
37822681-treated rats (Langlois et al., 2012) was not observed
at the higher oral dose levels employed in the rat repeat dose
toxicology studies with this compound. In the modified Irwin’s
test, however, catalepsy was observed in rats after a single oral
dose administration of 160 mg eq. kg–1
JNJ-37822681, but not
at 10 or 40 mg eq. kg–1
. In that study, sedation was observed at
all dose levels. In addition, abnormal gait (shuffling movement
and/or inability to walk after stimulation) was observed at 40
in addition flaccid body
tone and hypotonia were noted (unpublished results). It is
generally accepted that monkeys display a motor and behavioral
repertoire closer to that seen in humans than rats (Auclair et al.,
2009; Casey, 1993; Kumar et al., 2003) and that the nature of the
EPS-like behavioral changes in monkeys treated with antipsy-
chotics closely resemble those in patients (Casey, 1993).
Therefore, the monkey is generally considered a more predictive
animal model in terms of EPS liability in humans than the rat.
Both in the SAD trial in healthy male volunteers (te Beek et al.,
2012b) and in the 12-week clinical phase 2B trial with JNJ-
37822681 in patients with schizophrenia (Schmidt et al., 2012)
mild somnolence was the most frequently reported adverse
event. This observation is in line with the sedation reported as
hypoactivity in the monkey toxicology studies and reduced gen-
eral activity noted in the rat toxicology studies. In the SAD trial,
transient mild restlessness (akathisia) was reported in one volun-
teer at 20 mg, and by another volunteer at 15 and 20 mg of JNJ-
37822681. Mild musculoskeletal stiffness was reported by one
volunteer at 10 mg, and another one at 15 mg. Dose levels of
10 and 20 mg JNJ-37822681 affected motor function as
evidenced by a decrease in visuomotor coordination and finger
tapping rate, and an increase in body sway (te Beek et al.,
2012b). In the phase 2B trial the incidences of EPS-related ad-
verse events were similar between the placebo (n = 8 subjects;
incidence 8%), olanzapine at 15 mg once daily (n = 14; 15%)
and JNJ-37822681 at 10 mg twice daily (n = 14; 14%). The
Table 19. Mammary gland histopathology findings in the
6-month repeat dose toxicity study in Sprague–Dawley rats
Dose level
(mg eq. kg–1
day–1
)
0a
2.5 10 40
Males
19 19 19 19
Female aspect 0 0 0 19b
Fibrosis Slight 0 1 0 0
Females
19 19 19 19
Glandular
development
Minimal 17 11 1 0
Slight 2 8 18 16
Moderate 0 0 0 3
Secretion Minimal 2 4 10 3
Slight 0 0 2 3
Moderate 0 0 0 2
Focal fibroadenosis Minimal 0 0 2 1
Slight 0 0 0 1
Malignant lymphoma 0 1 0 0
a
Vehicle control.
b
Grade not scored.
Table 20. Mean toxicokinetic parameters of JNJ-37822681
in the 6-month repeat dose toxicity study in Sprague–Dawley
rats
Dose level
(mg eq. kg–1
day–1
)
2.5 10 40
Males, day 178
Cmax (ng h–1
ml–1
) 35.6 ± 12.7 138 ± 34.4 334 ± 118
AUC0–24 h (ngh–1
ml–1
) 103b
± 35.4 537 ± 35.4 2399 ± 815
Females, day 178
Cmax (ng h–1
ml–1
) 86.6 ± 21.1 225 ± 56.1 503 ± 82.1
AUC0–24 h (ngh–1
ml–1
) 387 ± 91.1 1,199 ± 26.7 3823 ± 352
a
b
n = 2 animals.

incidences were higher in patients treated with JNJ-37822681 at
20 (n = 21; 20%) or 30 mg twice daily (n = 39; 39%). The most
frequently reported EPS-related adverse events with JNJ-
37822681 in that trial were akathisia, tremors and parkinsonism.
With the exception of two reports of severe akathisia in the
30 mg JNJ-37822681 group, the adverse events of akathisia were
mild or moderate. All JNJ-37822681-dosed groups and the
olanzapine group showed antipsychotic activity, while the toler-
ability of the 10 mg twice daily dose level of JNJ-37822681 was
similar to that of olanzapine in terms of EPS side effects (Schmidt
et al., 2012). Although akathisia (defined as motor restlessness)
has been reported in monkeys treated with other dopamine
D2 receptor antagonists (Sachdev and Brüne, 2000), for
unknown reasons this behavior was not observed in the monkey
toxicology studies with JNJ-37822681. It should be noted that
the overactivity observed at 10 and 40 mg eq. kg–1
day–1
in the
morning before and at the time of dosing in the 6-month rat
study with JNJ-37822681 is not considered related to akathisia;
most probably it is a rebound effect subsequent to the underac-
tivity at these dose levels, which persisted to the end of the
working day but was not present anymore the next morning.
Unexpectedly, some JNJ-37822681-treated monkeys
exhibited visual hallucination-like behaviors, which apparently
were directed against seemingly non-existent stimuli. In fact,
these animals showed focused eye movements as if tracking
invisible objects. Aspects of this complex behavior were evident
in both the 1- and 9-month toxicology study. Remarkably, this
type of behavior was also observed in rhesus monkeys treated
with the D2 agonist quinpirole (Arnsten et al., 1995). Quinpirole’s
pharmacological action at the D2 receptor is the reverse of the
D2 antagonist JNJ-37822681. In patients with Parkinson’s disease
treated with dopamine D2 receptor agonists, visual hallucina-
tions are commonly observed (Fénelon et al., 2000). This is
generally not the case in patients with schizophrenia treated
with D2 antagonists. The reason why JNJ-37822681 induced
these behaviors in monkeys remains to be elucidated. In vitro
pharmacology experiments demonstrated that JNJ-37822681
has a low affinity to the 5-HT2 receptor (Langlois et al., 2012),
but at higher concentrations the compound did significantly
inhibit the binding of specific ligands at the 5-HT2 receptor
(unpublished results). This receptor is a prominent binding site
for several hallucinogenic drugs, and is associated with halluci-
nogenic behavior in humans and animals when modulated
(Ballanger et al., 2010; Manford & Andermann, 1998). Therefore,
it cannot be excluded that at high dose levels of JNJ-37822681
the 5-HT2 receptor is involved in the induction of psychomimetic
effects in monkeys.
In the phase 2B trial, the average prolactin levels in week 6
were similar in the placebo and 10 mg JNJ-37822681 groups,
but were elevated in the 20 and 30 mg JNJ-37822681 and
olanzapine treatment groups (Schmidt et al., 2012). Treatment-
emergent potentially prolactin-mediated adverse events
occurred across all dose groups, including controls at a very
low incidence (1–2%). As the duration of this trial was limited
to 12 weeks, potential long-term changes in prolactin levels
and prolactin-associated effects were not studied.
In the general toxicology studies with JNJ-37822681 in rats
hyperprolactinemia and hyperprolactinemia-mediated tissue
changes were evident. The prolactin elevation was observed
throughout the treatment period. These findings are in line with
the common notion that compared to other species, including
humans, the rat is prone to hyperprolactinemia and its sequelae
(Ben-Jonathan et al., 2008; Hargreaves & Harleman, 2011; Rehm
et al., 2007). In rat toxicology studies with dopamine D2 receptor
antagonists prolactin-mediated tissue changes commonly occur
in the female genital tract, male genital tract and male and female
mammary glands (Ben-Jonathan et al., 2008; Hargreaves &
Harleman, 2011; Rehm et al., 2007). Owing to the species-specific
luteotropic effects of prolactin a classic hallmark of
hyperprolactinemia in female rats is pseudopregnancy character-
ized by decreased cyclic activity resulting in an increased number
of rats being in permanent diestrus. Histopathological examina-
tion shows resting aspects of the uterus, ovaries and vaginal
epithelium. Female rats also demonstrate mammary gland stimu-
lation as evidenced by enhanced glandular development and
increased secretory activity. Mammary glands of male rats are
often affected as well showing a female appearance occasionally
associated with increased secretory activity (Ben-Jonathan et al.,
2008; Hargreaves & Harleman, 2011). In addition, male rats treated
with D2 antagonists often show increased (multi)focal inflamma-
tion of the dorsolateral prostatic gland (Ben-Jonathan et al.,
2008). The estrous cycle and associated hormonal fluctuations
are very different between rodents (4-day estrous cycle) and
primates. Monkeys (macaques) have an approximately 28-day
menstrual cycle (including menarche and menopause) and show
a high similarity to humans with regard to steroid metabolism
and mammary gland biology (Cline, 2007). The spectrum of
pseudopregnancy-like changes seen in rats given dopamine D2
receptor antagonists is therefore not relevant to humans.
In our rat experiments, the hyperprolactinemia persisted up to
6 months of dosing JNJ-37822681. Remarkably, the elevation of
circulating prolactin levels was transient over 24 h with a peak
during the first 2–6 h after dosing. The prolactin levels were at
baseline at 24 h after dosing. This rapid and short-lived prolactin
elevation was also observed with clozapine in rats (Rourke et al.,
2006). In contrast, risperidone caused a robust and persistent
increase in prolactin levels in rats up to and including the 24-h
postdose time point (Rourke et al., 2006). This difference in 24-h
time profile between clozapine and risperidone is also found in
the clinic. While clozapine is associated with a mild and transient
response over 24 h, the hyperprolactinemia with risperidone
maintains in patients up to 24-h postdose (Kapur et al., 2002;
Rourke et al., 2006). The translation of the 24-h time course of
prolactin elevations in rats to humans is known to be uncertain
(Rourke et al., 2006). In the phase 2B trial with JNJ-37822681 24-h
prolactin time curves were not established (Schmidt et al., 2012).
Hyperprolactinemia not only occurred in JNJ-3782681-treated
rats, but in monkeys as well. While there was no clear prolactin
elevation observed in the 1-month monkey study, the 3- and
9-month monkey studies revealed a transient prolactin increase
over 24 h, which remained present during the course of the
study. In this respect, to a large extent, the prolactin response
in monkeys resembled that in rats. However, in contrast to the
slight to moderate prolactin-mediated tissue changes in the rat
mammary gland, the histopathological examination of the
mammary gland in monkeys only revealed minor alterations.
Moreover, in the monkey mammary gland prolactin is not as
strong a mitogen as steroid hormones or growth hormone (Cline
& Wood, 2008). Consequently, the chance that breast tissue
changes will occur in JNJ-378226981-treated patients to a clini-
cally relevant extent is considered remote.
Dopamine D2 receptor antagonists have been associated with
hyperprolactinemia-mediated mammary tumors in rodents. As
no carcinogenicity studies with JNJ-37822681 have been

performed to date, it is unknown whether JNJ-37822681 induces
rodent mammary tumors upon chronic treatment. One female
rat dosed at 2.5mgeq. kg–1
day–1
in the 3-month study, however,
did show a mammary gland adenoma. Considering the changes in
the female genital tract across all dose levels in that study, this
finding was considered potentially treatment-related. There has
been a general consensus in the field over the last few decades
that prolactin-mediated mammary gland tumor responses in rats
and mice are not predictive of human breast cancer (Harleman
et al., 2012; Hargreaves & Harleman, 2011; Rudel et al., 2007; Russo
& Russo, 1996). However, recently this view has been challenged. It
has been claimed that prolactin acts as a tumor promoter in both
rodents and humans. Consequently, it cannot be excluded that
mammary tumorigenic findings in rodent carcinogenicity bioas-
says with dopamine D2 receptor antagonists do predict the occur-
rence of breast cancer in patients treated with these compounds
(Bernichtein et al., 2010; Harvey, 2005, 2011, 2012; Peveler et al.,
2008; Rudel et al., 2007). In the case of JNJ-37822681, no data exist
to either confirm or refute this hypothesis.
From the 12-week phase 2B trial it appears that JNJ-37822681
dosed at 10 mg twice daily showed a positive benefit to risk ratio
(i.e., efficacy with minimal to no weight gain, minimal metabolic
and EPS liability, and no prolactin elevating effects). This ratio
was less favorable at 20 and 30 mg twice daily (Schmidt et al.,
2012). The mean area under the plasma concentration–time
curve over the 12-h dosing interval (AUC0-12 h value ) was 380,
772 and 1107 ng h–1
ml–1
at 10, 20 and 30 mg twice daily; the
corresponding AUC0–24 h values were approximately 760, 1540
and 2200 ng h–1
ml–1
, respectively (unpublished results). There
is no exposure-based safety margin comparing the mean
AUC0–24 h value of 274–298 ng h–1
ml–1
at the NOAEL of 0.32 mg
eq. kg–1
day–1
in the 1-month monkey study and the mean
AUC0–24 h value of 760 ng h–1
ml–1
at 10 mg twice daily in the
phase 2B trial. This underscores that in the 1-month monkey
study EPS-like signs occurred at exposures where the incidence
of EPS was not increased over placebo in patients with schizo-
phrenia. In the 3-month monkey study, the NOAEL was higher
than in the 1-month study because of the gradual increase in
dose levels and exposures during the course of treatment. In
that study, the exposure-based safety margin was approximately
three-fold as derived from mean AUC0–24 h values of 2092 to
2163 ng h–1
ml–1
at the NOAEL of 2.5 mg eq. kg–1
day–1
. However,
in the 9-month monkey study a NOAEL could not be established
despite the fact that also in that study dose escalation took
place. Consequently, the latter study did not provide a safety
margin. It should be noted that the maximum treatment period
evaluated in the clinic only comprised 12 weeks, which does not
provide information on the long-term safety of JNJ-37822681 in
patients with schizophrenia. Moreover, the number of patients
involved was limited.
In conclusion, these investigations demonstrate that the toxi-
cological profile of JNJ-37822681 in cynomolgus monkeys and
Sprague–Dawley rats was different with respect to clinical
observations and mammary gland tissue changes, while both
species showed hyperprolactinemia. Monkeys predominantly
demonstrated EPS-like clinical signs, while rats mainly elicited
decreased general activity (sedation). Prolactin-mediated
mammary gland tissue changes were slight to moderate in rats,
and only minor in cynomolgus monkeys. At 10 mg twice daily,
the lowest efficacious human dose level of JNJ-37822681 tested
to date, the incidence of EPS-related adverse events and the
prolactin levels both were similar to placebo in patients with
schizophrenia. This beneficial safety profile confirms the hypoth-
esis that rapid dissociation from the dopamine D2 receptor can
reduce the risk of EPS and hyperprolactinemia observed with
current antipsychotic drugs in the clinic. Overall, the available
data suggest that the cynomolgus monkey showed better
predictivity towards the nature of JNJ-37822681-associated
adverse events in humans than the Sprague–Dawley rat.
Conflict of interest
Eric de Waal, Maria Desmidt and Ann Lampo are employees of
Janssen Pharmaceutica NV, a pharmaceutical company of
Johnson & Johnson. JNJ-37822681 is an experimental drug
owned by Janssen, Pharmaceutical Companies of Johnson &
Johnson. All studies described in this manuscript were funded
by Johnson & Johnson Pharmaceutical Research & Development,
currently designated as Janssen Research & Development.
Acknowledgements
The authors wish to thank Emma Hannaford for directing the
1-month monkey study with JNJ-37822681.
References
Andreasen NC. 2000. Schizophrenia: the fundamental questions. Brain
Res. Rev. 31: 106–112.
Anghelescu IG, Janssens L, Kent J, de Boer P, Tritsmans L, Daly EJ, van
Nueten L, Schmidt ME. 2012. Does early improvement predict
response to the fast-dissociating D2 receptor antagonist JNJ-37822681
in patients with acute schizophrenia? Eur. Neuropsychopharmacol.,
available on line 18 September 2012, http://ac.els-cdn.com/
S0924977X12002507/dx.doi.org/10.1016/j.euroneuro.2012.08.017
Arnsten AFT, Cai JX, Steere JC, Goldman-Rakic PS. 1995. Dopamine D2
receptor mechanisms contribute to age-related cognitive decline:
the effects of quinpirole on memory and motor performance in
monkeys. J. Neurosci. 15(5): 3429–3439.
Auclair AL, Kleven MS, Barret-Grévoz C, Barreto M, Newman-Tancredi A,
Depoortère R. 2009. Differences among conventional, atypical and
novel putative D2/5-HT1A antipsychotics on catalepsy-associated
behavior in cynomolgus monkeys. Behav. Brain Res. 203: 288–295.
Ballanger B, Strafella AP, van Eimeren T, Zurowski M, Rusjan PM, Houle S,
Fox SH. 2010. Serotonin 2A receptors and visual hallucinations in
Parkinson disease. Arch. Neurol. 67(4): 416–421.
Ben-Jonathan N, LaPensee CR, LaPensee EW. 2008. What can we learn
from rodents about prolactin in humans? Endocr. Rev. 29: 1–41.
Bernichtein S, Touraine P, Goffin V. 2010. New concepts in prolactin
biology. J. Endocrinol. 206: 1–11.
Boyda HN, Tse L, Procyshyn RM, Honer WG, Barr AM. 2010. Preclinical
modesl of antipsychotic drug-induced metabolic side effects. Trends
Pharmacol. Sci. 31: 484–497.
Casey DE. 1993. Serotonergic and dopaminergic aspects of neuroleptic-
induced extrapyramidal syndromes in nonhuman primates. Psycho-
pharmacology (Berl) 112: S55–S59.
Casey DE. 1996. Behavioral effects of sertindole, risperidone, clozapine
and haloperidol in Cebus monkeys. Psychopharmacology (Berl) 12:
134–140.
Cline JM. 2007. Assessing the mammary gland of nonhuman primates:
effects of endogenous hormones and exogenous hormonal agents
and growth factors. Birth Defects Res. (Part B) 80: 126–146.
Cline JM, Wood CE. 2008. The mammary glands of macaques. Toxicol.
Pathol. 36: 130S–141S.
Dickson RA, Glazer WM. 1999. Neuroleptic-induced hyperprolactinemia.
Schizophr. Res. 35: S75–S86.
Fénelon G, Mahieux F, Huon R, Ziégler M. 2000. Hallucinations in
Parkinson’s disease. Prevalence, phenomenology and risk factors.
Brain 123(4): 733–745.
Fukuoka T, Nakano M, Kohda A, Okuno Y, Matsuo M. 1997. The common
marmoset (Callithrix jacchus) as a model for neuroleptic-induced
acute dystonia. Pharmacol. Biochem. Behav. 58(4): 947–953.

JAT2916-published on line-19 Sept 2013

JAT2916-published on line-19 Sept 2013

Recommended

Recommended

More Related Content

What's hot

What's hot (10)

Viewers also liked

Viewers also liked (10)

Similar to JAT2916-published on line-19 Sept 2013

Similar to JAT2916-published on line-19 Sept 2013 (20)

More from Sven Korte, Dr. PhD.

More from Sven Korte, Dr. PhD. (8)

JAT2916-published on line-19 Sept 2013