Oecd guidelines for toxicology studies

toxicology study according to OECD guidelines, organisation for economic co-orporation and developement, jasdeep singh , maharaja ranjit singh punjab technical university bathinda

1. OECD Guidelines For Toxicology Studies JASDEEP SINGH M.Pharm (Pharmacology) 2/21/2018 1

2. CONTENT INTRODUCTION TO TOXICOLOGY OECD GUIDELINE FOR ACUTE ORAL TOXICITY LD50/LC50 Methods to calculate LD50 Limitation of LD50 H ow 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) 2/21/2018 2

3. OECD 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 . S et international standards on a wide range of things, from agriculture and tax to the safety of the chemicals . 2/21/2018 3

4. OECD 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. 2/21/2018 4

5. OECD 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. 2/21/2018 5

6. WHAT IS TOXICOLOGY? 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. 2/21/2018 6

7. ADVERSE DRUG EFFECTS 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 . 2/21/2018 7

8. ANIMAL TOXICITY TESTS Acute toxicity 14 days Sub-acute(repeated doses) 28 days toxicity. Sub-chronic toxicity 3 months Chronic toxicity 6to12month 2/21/2018 8

9. ACUTE ORAL TOXICITY 2/21/2018 9

10. ACUTE TOXICITY SYMPTOMS Tremor Salivation Muscle spasm Lacrimation Weightloss Diarrhoea Altered Respiration Loss of Righting reflex Convulsion 2/21/2018 10

11. LD 50 LC 50 WHAT IS LD 50 ? LD 50 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 LD 50 dose, the more toxic the pesticide. WHAT IS LC 50 ? The concentrations of the chemical in air that kills 50% of the test animals during the observation period is the LC 50 value. Other durations of exposure (versus the traditional 4 hours) may apply depending on specific laws. 2/21/2018 11

12. LD 50 LC 50 2/21/2018 12

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15. HOW OECD GUIDELINES MORE HUMANE ? 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). 2/21/2018 15

16. CONTINUE … 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. Refinement of the traditional acute oral test in that it requires fewer, but fixed, dosage groups to be tested, and thus fewer animals 2/21/2018 16

17. SOME ALTERNATIVES TO THE USE OF ANIMALS IN TESTING I n vitro (test tube) test methods and models based on human cell and tissue cultures. C omputerized 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). 2/21/2018 17

18. OECD GUIDELINES FOR ACUTE ORAL TOXICITY 2/21/2018 18

19. DESIGN OF ACUTE TOXICITY 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. 2/21/2018 19

20. ACUTE ORAL TOXICITY OECD GUIDELINES NO.401 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. 2/21/2018 20

21. ACUTE ORAL TOXICITY GUIDLINE NO. 420 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. 2/21/2018 21

22. CONTINUE … Reproducible procedure. Causes less suffering to the animals. Uses only moderately toxic doses, doses expected to be lethal should be avoided . Uses fewer animals 2/21/2018 22

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25. PROCEDURE 2/21/2018 25

26. FLOW CHART FOR SIGHTING STUDY 2/21/2018 26

27. FLOW CHART FOR MAIN STUDY 2/21/2018 27

28.   Globally Harmonized System  (GHS)  2/21/2018 28

29. ACUTE ORAL TOXICITY GUIDLINE NO.423 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 LD 50 Death of a proportion of animals as the major end point (response). Ld 50 cut off values are indicated. 2/21/2018 29

30. PRINCIPLE 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 2/21/2018 30

31. ACUTE ORAL TOXICITY GUIDLINE NO.425 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 LD 50 . 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 . 2/21/2018 31

32. CONTINUE … Animal receives 1st dose a step below the level of the best estimate of LD 50 . 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 2/21/2018 32

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34. COMPARISON OF GUIDELINES OF LD50 2/21/2018 34

35. LIMITATION OF METHODS USED FOR TOXICITY STUDY 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. 2/21/2018 35

36. CARCINOGENICITY STUDY 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 2/21/2018 36

37. OBJECTIVES 2/21/2018 37

38. HOUSING AND FEEDING H oused individually or in a group of 3 Maintain temperature at 22˚C ( ± 3˚C). R elative humidity should be at least 30% (50-60%) A rtificial lighting, 12 hours light and 12 hours dark cycle C onventional laboratory diets + unlimited supply of drinking water Analytical information on the contaminant levels should be generated periodically 2/21/2018 38

39. ANIMAL TO BE USED 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 T he weight variation of animals used should not exceed ± 20 % of the mean weight Animals should be randomly assigned 2/21/2018 39

40. DOSE GROUP AND DOSAGE 2/21/2018 40

41. OBSERVATIONS 2/21/2018 41

42. RESULT 2/21/2018 42

43. RESULT 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 2/21/2018 43

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