PRECLINICAL EVALUATION OF DRUG AND ITS IMPORTANCE IN CR INTRODUCTION Before a pharmaceutical company can initiate testing in humans, it must conduct extensive preclinical or laboratory research. This research typically involves years of experiments in animal and human cells. DEFINITION Preclinical study Research using animals to find out if a drug, procedure, or treatment is likely to be useful. Preclinical studies take place before any testing in humans is done. OBJECTIVES OF PRECLINICAL STUDY • • • • Support for human pharmacology. Support for human toxicology. Prediction of human pharmacokinetics. Screening new dosage forms and formulations. PHARMACOLOGY AND TOXICOLOGY IN ANIMALS • • • • • Extensive in-vitro & in-vivo experiments (Efficacy). Establishing molecular targets of drug actions. Pharmacokinetic properties, ADME. Short-term & long-term toxicity (Safety). Special toxicological testing. COMPONENTS OF PRECLINICAL DRUG DEVELOPMENT In VITRO STUDIES: Cell cultures Molecular targets PRECLINICAL DEVELOPMENT IN VITRO STUDIES PHARMACOLOGY: Molecular mechanisms of action and targets. Mechanisms of drug resistance Determinants of response Intracellular pharmacodynamics Molecular pharmacology Eg: In vitro studies of anticancer agents. The 3Rs principles eplacement of animal tests by methods not using animals. eduction: reducing the numbers of animals needed to answer a scientific question. efinement: reducing pain and distress in a particular animal experiment. COMPONENTS OF PRECLINICAL DRUG DEVELOPMENT In VIVO STUDIES: Animal models Efficacy Toxicity PRECLINICAL DEVELOPMENT IN VIVO STUDIES ANIMAL MODELS: Proof of therapeutic principle. Animal pharmacokinetics and pharmacodynamics. Toxicology. Starting dose and schedule for clinical trials. Lab Animals Non Human Primates Chimpanzee Long tail Macaque Pig tail Macaque Rhesus Macaque Marmosets Sq. Monkey Rodents Rat, Mouse, Hamster, Guinea pig Non Rodents Rabbit, Ferret, Dog, Cat , Mini pigs, occasionally other animals Research Animals SOURCE OF ANIMALS Animal shelters Specialist dealers like B & K universal laboratories ,UK. Covance, US. Huntingdon life sciences, UK. Charles river laboratories.Inc Animals Rats and Mice Usage Screening, hypertension, cancers, to test toxicity, specific gene function, viral & bacterial infections. Heart and respiratory diseases,develop surgical devices, used to overcome immune system rejection. Neurological studies, occular diseases, Hearing disorders. Rh disease, malaria, parkinsonism, Spinal cord injuries, HIV/AIDS Dogs Cats Primates Toxicology In toxicology, LD50 (abbreviation for “Lethal Dose, 50%”) of a toxic substance or radiation is the dose required to kill half the members of a tested population. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. The test was created by J.W. Trevan in 1927 but is now being phased out in favor of the Fixed Dose Procedure. Toxicity Studies 1. Acute toxicity tests 2. Sub acute toxicity studies 3. Repeated-dose toxicity studies 4. Long term toxicity studies 5. Reproduction studies a. Fertility studies b. Teratogenicity studies c. Perinatal studies 6. Local toxicity studies dermal, photoallergy/toxicity, vaginal, rectal, ocular, inhalation 7.Allergenicity/ hypersensitivity 8.Genotoxicity/ Mutagenicity 9. Carcinogenicity Importance of preclinical study: Give information about data on acute toxicity, kinetics & metabolism of the drug and organ sensitivity. To determine if the proposed clinical protocols in man are reasonably safe to initiate. Estimate a “safe” starting dose for phase I clinical study. To inform clinical investigators about the animal toxicities associated with the compound. To determine the safety monitoring measures. LIMITATIONS OF PRECLINICAL STUDY Toxicity testing is time-consuming & expensive. Large numbers of animals must be used. Extrapolation of toxicity data from animals to humans is not completely reliable. Rare adverse effects are unlikely to be detected. ROLE OF „PETA‟!!! In 1997, People for Ethical Treatment of Animals (PETA) filmed staff inside Huntingdon Life Sciences (HLS) in the UK, Europe's largest animal-testing facility, hitting puppies, shouting at them, and simulating sex acts while taking blood samples. Footage shot inside HLS in the U.S. appeared to show technicians dissecting a live monkey. The employees were dismissed and prosecuted, and HLS's licence to perform animal experiments was revoked for six months. A monkey in a restraint tube filmed by PETA in Covance laboratory in Vienna, Virginia 2004-05 ACTS AND GUIDELINES Animal Welfare Act (1966). NIH – The Guide For The Care and Use of Laboratory Animals(1985). Institute of Animal Care & Use Committee. Appendix III of SCHEDULE Y. GLP guidelines. Alternative methods In vitro research Computer and mathematical modeling Genetic research Autopsies Tissue culture tests Alternatives developed and „validated‟ in the last decade Animal model NCA | The Netherlands Centre Alternatives to Animal Use Alternative model tissue culture tests cell culture test cell culture test LLNA test Elisa test, ToBI test in vitro production 3 alternative approaches LAL test and in vitro model skin corrosivity test phototoxicity tests embryotoxicity tests skin sensitization test potency testing of tetanus vaccine monoclonal antibody production classical LD50 tests pyrogenicity testing Conference ‘Europe Goes Alternative’, Brussels, 071105 Alternatives developed and „validated‟ in the last decade (contd…..) Animal model Alternative model antigen quantification PCR & transgenic animals Elisa test Elisa tests antigen quantification potency test hepatitis vaccine neurovirulence test polio vaccine potency test erysipelas vaccine potency test various close tridial vaccines potency test leptospirosis vaccine potency test rDNA physico-chemical tests COMPARITIVE STUDY USE OF ANIMALS 14 USE OF ALTERNATIVES 14 No. animals (x million) No.animals (x million) 12 10 8 6 4 2 0 12 10 8 6 4 2 0 6 203 0 203 4 202 0 202 4 201 8 200 2 200 6 199 6 206 4 205 2 204 0 203 0 202 8 200 6 199 INDIAN SCENARIO Historically India has maintained a share of 0.7% of the Preclinical Outsourcing market. Indian preclinical outsourcing market has the potential to reach USD 407 million by 2010. Some private players in India are: Rallis research centre, Bangalore. JRF, Ahmedabad. Intox, Pune. Sipra Laboratories, Hyderabad. Syngene, Bangalore. Conclusion Future will give a shift in research and regulatory testing paradigms Non-animal models will increasingly being used to generate answers to the „why‟ questions while the animal model will be used to verify and confirm data from non-animal studies REFERENCES http://www.aphis.usda.gov/ac/publications.html Schedule Y (Ministry Of Health & Family Welfare). Questions People Ask About Animals in research. (American physiological society) http://www.allchemeseminars.org/downloads/07-0503/EuropeanParliament1.pdf Less animals make more science and more science makes better Regulations.
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