2. ⦿INTRODUCTION
⦿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)
3. ⦿ 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. ⦿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
5. ⦿India is one of the many non-member
⦿The OECD Council at Ministerial level
adopted a resolution on 16 May 2007 to
economies with which the OECD has working
relationships in addition to its member
countries.The OECD has been co-operating with
India since 1995
strengthen the co-operation with India, as with
Brazil, China, Indonesia and South Africa, through
a programme of enhanced engagement
6. ⦿Any undesirable &/ or unintended effects of
drug.
1. Predictable (typeA 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.
7. ⦿Acute toxicity 14 days
⦿Sub-acute(repeated doses)
toxicity.
28 days
⦿Sub-chronic toxicity 3 months
⦿Chronic toxicity 6to12month
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.
11.
12. ⦿ 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 end
point
⦿ 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).
13. Procedure
impending
(425), use
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
⦿ 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
14. ⦿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).
15.
16. ⦿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.
17. ⦿ 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.
18. ⦿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
⦿T
esting in 1 sex usually females is considered sufficient
19. ⦿Reproducible procedure.
⦿Causes less suffering to the animals.
⦿Uses only moderately toxic doses, doses expected
to be lethal should be avoided.
⦿Uses fewer animals
19
4/17/2018
23. ⦿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).
⦿Ld50 cut off values are indicated.
24. ⦿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
25. ⦿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
26. ⦿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
27.
28. ⦿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.
29. ⦿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 levels,
including signs of toxicity
⦿Duration of clinical observations
⦿Ophthalmological examination
⦿Haematological tests
⦿Clinical biochemistry tests
