Screening methods in pharmacology

As per JNTUH syllabus

1. Screening Methods in Pharmacology As per PCI ( 3-2 ) syllabus. Course – B . pharmacy . JNTUH B . Tanuja B . Pharmacy final year student. SCP

2. UNIT – I INDEX 1. Care and Handling of laboratory animals. 2. Breeding techniques of laboratory animals. 3. Regulations for laboratory animals. 4. CPCSEA Guidelines. 5. Alternative to animal studies.

3. 1. Care and Handling of laboratory animals It is generally essential for the students belonging to different fields like zoology , veterinary medicines etc. This method is mainly helpful to observe, take care, dissect and experiment the laboratory animals. It is used for the development of human medicines involved in the treatment like Chemotherapy, Polio , Diphtheria etc. It is also used in the development of veterinary medicines. The government of respective countries have established several rules and regulations concerned with the use of laboratory animals.

4. General principle It requires safe and responsible handling. Handling and physical control of small and large animals should be performed. Institution should employ people who are trained pharmacologists, veterinary scientists etc for handling of laboratory animals.

5. Methods of handling laboratory animals The laboratory animals which are commonly used in the experiments are – a. Mice b. Rats c. Rabbits d. Guinea pig e. Hamsters

6. a. Mice Mice can bite if mishandled so , they should be handled carefully without making any sudden or quick movement. Place mice on a surface where they can be gripped easily. Holding the tail base securely, pull back gently to stimulate the animal to grip. Now , use the other hand to grasp the loose skin at the back of the neck between the thumb and forefinger. The mice is now ready to get injected or examined.

7. b. Rats Rats are quiet and non-aggressive animal . Hence , they can be controlled easily. They bite only when they are under-stress or in pain. Handling of rats are similar to that of mice. However , the tail base should be grasped carefully.

8. c. Rabbits Rabbits are susceptible to stress hands . So ,they should be always handled in calm and confident manner. Rabbits are highly susceptible to lumber dislocation and also they gets paralyzed easily. Rabbits should be handled gently by placing one hand under the chest and the other hand supporting back legs of the animal securely. Rabbits should never be carried or lifted by their ears as it causes pain to them.

9. d. Guinea pig These are small animals with short ears and no tail. They get scared easily . Hence , they should be handled quickly , carefully and easily. They usually don’t bite and produce sound to prevent stress. For handling guinea pig , the animal should be approached in a calm and confident manner. Place one hand under the chest and the other hand supporting the back.

10. e. Hamsters Hamsters are animals that looks like large rat but with no tail. They should be handled in a manner similar to that of Rats. They should be placed over a bench or table for handling as they often try to escape and get injured.

11. 2. Breeding techniques of laboratory animals Animal breeding is referred to the process of reproduction of animals under controlled conditions. Breeding techniques are used to improve as well as to produce better animal breeds . Breeding techniques can be mainly categorized into two types – (1) In-breeding (2) Out-breeding

12. (1) Inbreeding Inbreeding refers to the process of mating of related animals . This process involves crossing of closely related animals like mating between father and daughter , brother and sister . Inbreeding is most commonly used in laboratory rats and mice and some breeds of dogs . Inbreeding can be mainly classified into two types – (a) Close breeding (b) Line breeding

13. (a) Close breeding It refers to the mating of male and female child of the same parent ( full brother and full sister ). Female parent with her male child (son) and Male parent with his female child (daughter) . It is the most intense form of inbreeding and it should be employed only if their both the parents are of high quality .

14. (b) Line breeding It refers to the mating of related animals that don’t belong to the same parent . In other words , the breeding of animal that share common ancestors is termed as Line breeding .

15. (2) Out breeding Out breeding refers to mating of unrelated animals i.e. individuals from different populations , sub – species , species . It is mainly divided into four types – (a) out crossing (b) cross breeding (c) species hybridization (d) Grading up

16. (a) Out crossing It refers to the mating of unrelated animals of the same breed . The aim behind this breeding technique is to mate unrelated animals considered to be genetically superior for certain traits as well as to introduce new genetic material to the family .

17. (b) Cross breeding It refers to the mating of animals of different breeds . Cross breeding generally results in the production of new breeds . They have improved traits because the dominant genes have masked the undesirable , recessive genes . It can be further classified into three types – a. Crisscrossing b. Triple crossing c. Back crossing .

18. (c) Species hybridization It involves mating of animals from different strains , species etc. Due to the crossing of these unrelated animals , the resulted progeny acquires relatively more strength than its parent . (d) Grading up It refers to the mating of animals of two different breeds . Here , the animals of an indigenous breed is mated by an improved pure breed of several generations. Grading up is continuous use of purebred sires of the same breed in a grade herd .

19. 3 . Regulations for laboratory animals The Animal Welfare Act (AWA), ensures minimum standard of care and treatment that should be provided to certain animal breeds for research , commercial sale etc . It provides suitable diet and environment to the laboratory animals . It also protects the animals from pain , sufferings and diseases . It mainly focuses on - Freedom from hunger and thirst . Freedom from discomfort . Freedom from pain , injury and disease .

20. 4 . CPCSEA guidelines CPCSEA stands for the Committee for the Purpose of Control Supervision of Experiments on Animals . It is a statutory committee of Department of Animal Husbandry and Dairying ( DAHD ) , Ministry of Fisheries constituted under the PCA Act, 1960. CPCSEA is a duty bound to take all necessary measures to ensure that animals are not subjected to unnecessary pain or suffering before , during (or) after experimenting on them . The main aim of these guidelines is to promote the human care of animals used in research .

21. Veterinary care it requires daily observation of adopted animals by a veterinarian . Quarantine – (a) For small lab. animals = 1 week to 1 month (b) For large lab. animals = up to 6 week Stabilization – Physiological , psychological and nutritional stabilization is required . Separation – Physical separation of animals by their species is required in order to prevent anxiety and behavioral changes of the animal .

22. Animal procurement and transportation Procurement of animals is done from established commercial animal vendors . During transportation , stress hands are avoided by using appropriate size of transport containers . Experimental area – Experiments should be carried out in a separate area , away from the place where they are housed . There should be separate functional areas for surgical support and treatment of animals .

23. Physical facilities - (a) Building materials should be fire resistant and moisture proof . (b) Corridor should be wide enough for movement . (c) Floor should be smooth and moisture proof . (d)Temperature must be between 18-29*c . (e) Proper ventilation and proper drainage system should be provided . (f) Power and lightning system should be safe . (g) Noise free environment is required . (h) storage area .

24. Animal Husbandry Caging or Housing System – Adequate space, freedom of movement . Comfortable environment . Easy access to food and water . Proper ventilation. Food and water – Food should be palatable . Food should be nutritionally adequate . Food should contain moisture , crude fiber, Protein and fats . Should have easy and continuous access to fresh and uncontaminated drinking water .

25. Sanitation and cleanliness - a ) Proper maintenance of records . b ) Proper selection of animal facility staff is required .

26. 5 . Alternative to animal studies It is an advanced computerized modeling technique which uses human cells and tissues (in-vitro ). Scientists often study the effects of drugs and chemicals on animals before they declare them safe for humans . Alternative testing methods offers many advantages over Animal testing method, they are not only cost effective and rapid but are also more reliable than the animal tests .

27. 3 R’S of alternative testing The concept of 3R’S stands for Reduction , Replacement and Refinement . 1. Reduction – It refers to minimizing the number of animals required for an experiment to a minimum level. This test method aims in – (a) Prevention of duplication . (b) Species and animal model selection . (c) Experimental design .

28. 2 . Replacement Replacement of animals often means the usage of computer model as an alternative study . It is also termed as “Absolute replacement” . Absolute replacement may involve usage of human cells and tissues . Several tests performed under replacement method – Skin absorption test For animal test – test chemical is applied to shaved skin of the rat’s back and observed for a period of 24 hours . For non-animal test – the test chemical is applied on the treated skin (tissue culture ) and observed for a period of time .

29. b) Pyrogenicity Pyrogens are fever and inflammation causing agents . Pyrogenicity tests determines the potential presence of Pyrogens . Animal test – The test chemical is injected into the blood stream of the rabbit and the temperature is recorded periodically . Non- animal test – in-vitro test using donated human blood as a test medium .

30. c) Immunotoxicity This test is mainly used as an alternative for guinea pig to screen for allergic reaction Immunization Fusion of lymphocytes Separation of hybrid cells Screening of hybrid cells Cloning of hybrid cells

31. 3. Refinement It is a test method that eliminates pain , sufferings and distress in animals ( or) enhances animal wellbeing by providing better housing enrichment . Refinement not only considers animal during the experiment but also considers the wellbeing of the animals from birth till death .

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