Oecd guidelines for toxicology studies

OECD Guidelines
For
Toxicology
StudiesJASDEEP SINGH
M.Pharm(Pharmacology)
4/17/2018 1

 INTRODUCTION TO TOXICOLOGY
 OECD GUIDELINE FOR ACUTE ORAL TOXICITY
 LD50/LC50
 Methods to calculate LD50
 Limitation of LD50
 How OECD GUIDELINES More Humane?
 Alternatives to use of Animal in AOT
 Description of Whole AOT Guidelines along with
Its Sighting Study (401,420,423,425)
4/17/2018 2

 The mission of Organisation for Economic
Co-operation and Development is to
promote policies that will improve the
economic and social well-being of people
around the world.
 work with governments to understand what
drives economic, social and environmental
change.
 Set international standards on a wide range
of things, from agriculture and tax to the
safety of the chemicals.
4/17/2018 3

 The Organisation for European Economic
Cooperation (OEEC) was established in 1948
to run the US-financed Marshall Plan for
reconstruction of a continent ravaged by war.
 Canada and the US joined OEEC members in
signing the new OECD Convention on 14
December 1960.
 The Organisation for Economic Co-operation
and Development (OECD) was officially born
on 30 September 1961, when the Convention
entered into force.
4/17/2018 4

 India is one of the many non-member
economies with which the OECD has working
relationships in addition to its member
countries.The OECD has been co-operating
with India since 1995.
 The OECD Council at Ministerial level
adopted a resolution on 16 May 2007 to
strengthen the co-operation with India, as
with Brazil, China, Indonesia and South
Africa, through a programme of enhanced
engagement.
4/17/2018 5

 Toxicology is the scientific study
of adverse effects that occur in
living organisms due to
chemicals.
 It involves observing and
reporting symptoms,
mechanisms,detection and
treatments of toxic substances,
in particular relation to the
poisoning of humans.
4/17/2018 6

 Any undesirable &/ or unintended effects of
drug.
1. Predictable (type A reactions)
2. Non-predictable (type B reactions)
SIDE EFFECTS
Unwanted but often
Unavoidable effects at
therapeutic doses.
SECONDARY EFFECTS
Indirect consequences
of primary action of
drug
TOXIC EFFECTS
Are results of excessive
Pharmacological effect
of drug due to over
dosage or prolonged
use.
4/17/2018 7

 Acute toxicity 14 days
 Sub-acute(repeated doses) 28 days
toxicity.
 Sub-chronic toxicity 3 months
 Chronic toxicity 6to12month
4/17/2018 8

TEST GUIDELINES
NUMBERS
401 420 423 425
4/17/2018 9

Tremor
Salivation
Muscle spasm
Lacrimation
Weightloss
Diarrhoea
Altered Respiration
Loss of
Righting reflex
Convulsion
4/17/2018 10

WHAT IS LD50 ?
 LD50 represents the individual dose required to kill
50% of a population of test animals.
 It is an index determination of medicine and poison’s
virulence.
 Lower the LD50 dose, the more toxic the pesticide.
WHAT IS LC50?
 The concentrations of the chemical in air that kills
50% of the test animals during the observation period
is the LC50 value.
 Other durations of exposure (versus the traditional 4
hours) may apply depending on specific laws.
4/17/2018 11

 A humane endpoint can be defined as the
earliest indicator in an animal experiment of
severe pain, severe distress, suffering, or
impending death.
 OECD Test Guidelines do not require death as an
endpoint.
 Animals humanely killed during the test
will be regarded as dosage-dependent deaths.
 Three alternative test methods (Guidelines 420,
423,and 425) to the traditional acute oral
toxicity test have been adopted by the OECD.
One of these, the Fixed Dose Procedure
(Guideline 420).
4/17/2018 15

 It also employs non-
lethal endpoints to
determine the toxicity
of the test substance.
 Two other methods,
the Acute Toxic Class
Method(423) and the
Up-and-Down
Procedure (425), use
impending death as
the only endpoint.
o Refinement of the traditional acute oral test in
that it requires fewer, but fixed, dosage groups
to be tested, and thus fewer animals
4/17/2018 16

 In vitro (test tube) test methods and models
based on human cell and tissue cultures.
 Computerized patient-drug databases and virtual
drug trials.
 computer models and simulations.
 stem cell and genetic testing methods.
 non-invasive imaging techniques such as MRIs
and CT Scans.
 microdosing (in which humans are given very low
quantities of a drug to test the effects on the
body on the cellular level, without affecting the
whole bodysystem).
4/17/2018 17

 14 days study.
 Study on at least two species.
 One rodent –mice/rat.
 One non rodent –usually rabbit.
 Dose administered orally & parenterally.
 Various dose levels to groups of both
sexes.
 Dose selection such that causing less
than50% but not 0% and more than 50%
but not 100% mortality.
4/17/2018 19

 In a study of toxic characteristics of substance, acute
oral toxicity testing is initial step.
 Gives information on health hazards.
 Test substance administered orally, in graduated doses
to several groups of experimental animals.
 One dose used per group.
 At least 5 rodents at each dose level of same sex are
used.
 Observations for effects & death are made.
 After completion of study in one sex, study in another
sex is carried out.
 Studies suggested in rodents but can be adopted for
studies in non-rodents.
4/17/2018 20

 New approach in 1984 by British toxicology
society
 based on administration of series of fixed
dose levels.
 Instead of death, clear signs of toxicity to
animals as end point.
 Adopted as 1st alternative to conventional
acute toxicity test.
 Testing in 1 sex usually females is
considered sufficient.
4/17/2018 21

 Reproducible procedure.
 Causes less suffering to the animals.
 Uses only moderately toxic doses, doses
expected to be lethal should be avoided.
 Uses fewer animals
4/17/2018 22

Procedure
involves 2 step
1- sighting
study
2-main
study
4/17/2018 25

 No sighting study.
 3 animals of single sex per step.
 On avg. 2-4 steps may be necessary to allow
judgment on the acute toxicity of the test
substance.
 Not intended to allow the calculation of
precise LD50
 Death of a proportion of animals as the
major end point (response).
 Ld50cut off values are indicated.
4/17/2018 29

 Stepwise procedure with the use of
minimum no.of animals per step.
 Substance administered orally to 2 groups
of animals at defined doses .
 3 animals per step of single sex (normally
females).
 Compound related mortality determines
the nextstep.
 Report
4/17/2018 30

 Up and down testing approach was 1st
described by Dixon and Mood.
 Bruce in 1985 proposed to use it for acute
toxicity determination of chemicals.
 Estimates confidence intervals for LD50.
 In procedure (main test ) 1-animal dosed at a
time, at minimum of 48 hrs interval.
 Suggested starting dose is 175 mg/kg or can
be selected from 1.75, 5.5,
17.5,55,175,550,2000mg/kg .
4/17/2018 31

 Animal receives 1st dose a step below the
level of the best estimate of LD50 .
 Depending upon the outcome for the
previous
 animal, the dose for the next animal is
adjusted up or down.
 5 reversal in 6 consecutive animals when
obtained test is terminated.
 No. of animals limited to 15.
 Report
4/17/2018 32

 Indicated that all are likely to perform poorly
for chemicals with shallow dose-response slopes
Because Guideline 420 uses evident toxicity as
an endpoint instead of death.
 Unusually test substances may cause delayed
deaths (5 days or more after test substance
administration) mostly in case of 425
However, both in Guideline 420 and 423, the
finding of a delayed death may require
additional lower dose levels to be used or
study to be repeated.
4/17/2018 35

 The test substance is administered daily in
graduated doses
 Observed closely for signs of toxicity and for
the development of neoplastic lesions.
 Died or are killed animals are necropsied and
at the conclusion surviving animals are also
killed and necropsied.
451
4/17/2018 36

 Housed individually or in a group of 3
 Maintain temperature at 22˚C (± 3˚C).
 Relative humidity should be at least 30% (50-
60%)
 Artificial lighting, 12 hours light and 12 hours
dark cycle
 Conventional laboratory diets + unlimited
supply of drinking water
 Analytical information on the contaminant
levels should be generated periodically
4/17/2018 38

 Rodents/non-rodents used
 2 months study for rodents
 90 days study for non-rodents
 Mostly mice are used due to short life-span
and susceptibility
 Healthy animals, acclimated to laboratory
conditions for 7 days and not been subjected
to previous experimental procedures
 The weight variation of animals used should
not exceed ± 20 % of the mean weight
 Animals should be randomly assigned
4/17/2018 39

 Survival data; urinalysis tests
 Outcome of any investigations of neurotoxicity
or immunotoxicity
 Terminal body weight; organ weights
 Necropsy findings; A detailed description of all
treatment-related histopathological findings
 Absorption data if available
 Body weight/body weight changes
 Toxic response data by sex and dose
level,including signs of toxicity
 Duration of clinical observations
 Ophthalmological examination
 Haematological tests
 Clinical biochemistry tests
4/17/2018 43

THANK YOU
Kindly !stay on Right Side while walking on the Road4/17/2018 45

Oecd guidelines for toxicology studies

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