Study of animal toxicity and Its guidelines.

1. Acute Subacute and
Chronic Toxicity in
Animals
Third Year PharmD.
Sub: Pharmacology
Abhijit Gaikwad 320
Saakshi Deokar 303

2.  Introduction
 OECD Guidelines { The organization for Economic
Co-operation and Development } test guidelines of
TG402, TG403 , TG420 , TG423 and TG425
describe acute systemic testing.
1. OECDTG420 – For fixed dose procedure.
2. OECD423 – For Acute toxic class method .
3. OECD425 – For up and down procedure .
4. OECD402 – For Acute dermal toxicity .
5. OECD403 – For Acute inhalation toxicity .

3.  Repeated Dose 28‐day Oral Toxicity Study in
Rodents (TG407)
 Repeated Dose 90‐Day Oral Toxicity Study in
Rodents (TG 408)
 Repeated Dose Dermal Toxicity: 21/28‐day Study
(TG 410)
 Sub chronic Dermal Toxicity: 90‐day Study (TG 411)
 Repeated Dose Inhalation Toxicity: 28‐day or
14‐day Study (TG 412)
 Sub chronic Inhalation Toxicity: 90‐day Study (TG
413)

4.  Repeated dose study or sub acute toxicity or chronic
toxicity .
 Two mammalian species { one should be rodent and
the second must not be rodent }
 Long period study for 30 to 180 days .Dose depends
on dose escalation studies.
 Drug administered by clinical route.
 Following Parameters are monitored and recorded :
● Behavioral
● Physiological
● Biochemical
● Microscopic

5.  Rodents and non rodents are used to study the sub chronic toxicity
of a substance.
 Dose to the therapeutic level can be, (daily) or expected therapeutic
level to increasing dose phase wise manner.
 The test Substance is administered orally for ≥ 90 days and regular
body weight variation biochemical and cardiovascular parameters
changes and behavioral changes are observed.
 At the end of the study the experimental animals are sacrificed gross
pathological changes are observed, and all the tissues are subjected
to histopathological analysis.
 There should be little individual Variation between the animals, and
the allowed weight variation range is ± 20%.
 Used to determine the maximum safe dose and nature of toxicity.
 Chronic toxicity studies are a minimum of 1 rodent and 1 non rodent
species.

6.  The test compound is administered over more than 90
days , and the animals are observed periodically at
regular intervals.
 A chronic toxicology study provides interferences about
long term effect of a test substance act in animals and it
may be extra foliated to the test substances.
 The report on Chronic oral toxicity is essential for new
drug entities. There should be little individual variation
between the animals and the allowable weight variation
range is ± 20%.

7.  Dose
● High dose produce significant retardation of growth of some
pathological changes .{ 10times the expected maximum clinical
dose }
 High range
 The low dose is about twice the expected maximum clinical dose.
 Medium Dose : It is fixed between high and low dose.
 During the study period animals are observed for normal
physiological functions , behavioural variations and alterations in
biochemical parental , at regular intervals {at least every 14 days}.
 At the end of the study , tissues are collected from all parts of the
animal and subjected to histological analysis.

8.  Types of Local Toxicity studies :
 Dermal Toxicity Study
Animals like :{Rats and Rabbits}
 Local signs
Signs like :{Erythema and Oedema}
 Histological Examinations.
 Dermal Photo toxicity study
{Animal used : Guinea pig}
Used in the treatment of Leukoderma
Also used in examination of Erythema and Oedema formation.
 Vaginal Toxicity studies.
{Animal used : Rabbit or Dog}
Used in observation of swelling and histopathology of vaginal wall.

9.  Types of Local Toxicity studies :
 Rectal tolerance studies
Animals used : {Rabbit and Dog}
Signs of pain , blood or mucous.
Histological examination of rectal mucosa.
 Ocular Toxicity Studies
Animal used : { Albino rabbit }
Observation done on basis of : Changes in cornea, iris , aqueous humor
and histological examination of eye.
 Parenteral Drugs : For IV , IM , SC , Intradermal injections .
 Inhalation Toxicity Study : 1 rodant and 1 non rodant .
Acute , Subacute and Chronic studies perform observation of
respiratory rate , histological examination of respiratory passages and
long tissue.

10.  Acute Toxicity Studies
 The Globally Harmonized System (GHS),defines it as "those
adverse effects occurring following oral or dermal administration
of a single dose of a substance, or multiple doses given within
24 hours, or an inhalation exposure of 4 hours"
 The preferred species for oral and inhalation testing is the rat,
and for dermal testing, the rat or rabbit
 Oral administration is the most common form of acute systemic
toxicity testing.

11.  Five Organisation for Economic Cooperation and
Development (OECD) Test Guidelines (TGs 402, 403,
420, 423, and 425) describe acute systemic testing.
 Fixed Dose Procedure (OECD TG 420)
 Acute Toxic Class method (OECD TG 423)
 Up‐and‐Down Procedure (OECD TG 425)
 Acute Dermal Toxicity OECD TG 402
 Acute inhalation toxicity OECD TG 403.

12.  SUBACUTE AND CHRONIC TOXICITY TESTING
● The Globally Harmonized System (GHS)defines it as "specific target organ/systemic toxicity
arising from a repeated exposure"
● Repeated dose toxicity testing using oral administration of a test substance in rodents for 28 and 90
days is used to evaluate chronic toxic effects, primarily effects on various organ systems, and to
establish a no observed effect level
● Chronic toxicity testing consists of oral, dermal, and inhalation sub acute repeated dose studies
(28‐day) and subchronic repeated dose studies (90‐day) in rodents.
● .The endpoints for repeat dose testing consist of an evaluation of clinical observations, blood
analysis, whole body gross necropsy, and microscopic examination of all organs and tissues
(histopathology)

13. The objectives of chronic toxicity studies covered by this
test guideline include:
 The identification of the hazardous properties of a
chemical
 The identification of target organs
 Characterization of the dose: response relationship
 Identification of a no‐observed‐adverse‐effect level
(NOAEL) or point of departure for establishment of a
Benchmark Dose (BMD),
The prediction of chronic toxicity effects at human
exposure levels, Provision of data to test hypotheses
regarding mode of action

14. REFERENCES
● www.alttox.org/trtc/chronictoxicity
● www.currentprotocols.com
● Lehman, A. J.Sewer trends in the laboratory evaluation of the safety of drugs.
● W. H. 0. (1966). Principles for preclinical testing of drug safety. Techn. Rep. Ser. 341
● Cooper RL, Lamb JS, Barlow SM et al (2006). ATiered Approach to Life StagesTesting
for AgriculturalChemical Safety Assessment.Critical Reviews inToxicology 36, 69‐98.
● Van den Heuvel, M.J., Dayan,A.D. and Shillaker, R.O. (1987). Evaluation of the BTS
approach to the testing of substances and preparations for their acute toxicity.
● HumanToxicol.‚ 6, 279‐291.

15. THANKYOU