General Principles of Preclinical Screening of CNS stimulant and CNS Depressant

Discover the fundamental principles and best practices for preclinical screening in drug development. This presentation provides an in-depth overview of the critical stages, methods, and considerations involved in evaluating potential drug candidates before human testing.

1. THE ERODE COLLEGE OF PHARMACY & RESEARCH INSTITUTE DEPARTMENT OF PHARMACOLOGY PHARMACOLOGICAL AND TOXICOLOGICAL SCREENING METHODS - I

2. General Principles of Preclinical Screening CNS Stimulants And CNS Depressants

3. CNS STIMULANTS Central Nervous System Stimulant may be used to reduce tiredness and increase alertness, competitiveness and aggression. CNS Stimulants may be defined as “ Drug substance that most specifically Afford an enhancement in excitability either very much within the different portions of the brain or the spinal cord which may lead to convulsion.

4. CLASSIFICATION OF CNS STIMULANT 1. ANALEPTICS Doxapram Nikethamide Picrotoxin Bicuculline 2. PSYCHOMOTOR STIMULANTS Amphethamine Cocaine Fenfluramine Phentemine 3. GENERAL CELLULAR STIMULANTS Methylxanthines Caffeine (Coffee) Theophylline (Tea) Theobromine (Chocolate)

5. EVALUATION METHODS Actophotometer Method Sand-Displacement Method Runway Test Open field Test Hole Board Test Thread wheel Method Rotarod Method Ptosis Test IN-VIVO METHOD

6. ACTOPHOTOMETER METHOD

7. Purpose : To Evaluate Locomoter Activity in Animals Principle : When the Beam of Light Falling on the Photo cell is cutoff by the animal, a count is recorded Procedure : Mice weighing 20-25 gm are divided into 3 groups, each contain 4 animals Control: Saline Standard: Amphetamine Test: Drug to be Evaluated Mice from each group is placed separately in Actophotometer for 10 min and Count the cutoff of light beam

8. Place each mice every 30 min till max effect of drug is observed Evaluation: Number of cut-off is compared between groups More cut-off: CNS stimulant Less cut-off: CNS depressant

9. SAND DISPLACEMENT METHOD

10. Purpose: To evaluate the motor activity in animals Principle: Drug like Caffeine stimulate the motoractivity in animal by inhibiting the adenosine transmission in the brain Procedure: A cage with sand is calibrated for amount of sand displaced per unit time Mice weighing 20-25 gm are divided into 3 groups, each contain 4 animals Control: Saline Standard: Caffeine (20 mg/kg) Test: Drug to evaluated

11. After 1 hour the animal is placed in cage for 15 min Evaluation: Volume of sand displacement in each group is compared More sand displacement: CNS stimulant activity Less sand displacement: CNS depressant activity

12. OPEN FIELD TEST

13. Purpose: To test anxiety, exploration and locomotion in animal Principle: Interruption of light beams as a measure of movements of rat or mice in an Open field Procedure: Open field arena with 2-Rows of 8-Photosensitive cells placed 40mm and 125 mm above the floor, respectively in constructed Adult male Sprague-Dawley rats with a weight between 280 and 320 g used Animal Placed in centre of area and observed Control: Saline Standard: Amphetamine Test: Drug to evaluated

14. Evaluation: a) Motor activity: All interruptions of photo beams in lower rows b) Rearing: All interruption of the photo beams in the upper rows Higher interruption : CNS stimulant activity Lower interruption : CNS depressant activity

15. HOLE BOARD TEST

16. Purpose: The evaluation of behaviour of mice such as curiosity or exploration Principle: An open field with holes on the bottom is used into which the animal could poke their noses which is a sign of curiosity Procedure: The hole board has size od 40 x 40 cm with sixteen holes having diameter of 3 cm each are distributed evenly on the floor Mice of either sex with a weight between 18 and 22 g are used Control: Saline Standard: Amphetamine Test: Drug to evaluated

17. Mice are placed on the Ho0le board and observed Evaluation: The numbered of counts for nose poking of treated animals is Calculated to that control animals Higher number of pocking : Higher Curiosity Lower number of pocking : Lesser Curiosity

18. CNS DEPRESSANTS Central Nervous System Depressant are type of drugs that slows down brain activity, which causes the muscles to relax and clams and soothes a persons making them useful for treating anxiety, panic, acute stress reaction, and sleep disorders.

19. CLASSIFICATION OF CNS DEPRESSANT 1. BARBITURATES Pentobarbital Phenobarbital Secobarbital Thiopental 2. BENZODIAZEPINES Diazepam Triazolam Midazolam Alprazolam 3. MISCELLANEOUS AGENTS Meprobamate Paraldehyde Chloral Hydrate Methaqualone

20. EVALUATION METHODS Forced Swim Test Tail Suspension Test Thread wheel Method Rotarod Method Benzodiazepine Induced Sleeping Time Ptosis Test IN-VIVO METHOD

21. FORCED SWIM TEST

22. Purpose : To check behavioral related activity Principle : Mice are placed in an inescapable tank that is filled with water and their Escape related motility Procedure : Mice weighing 20-30 gm are used Control: Saline Standard: Diazepam(1mg/kg) Test: Drug to be Evaluated Mice are kept in the water filled tank and its activity is observed

23. Evaluation: For mice, code the last 4 min defined as the test stage Duration of the spent as in the water tank Immobile : Potent CNS Depression Struggling/Climbing : Moderate CNS Depression Swimming : No CNS Depressant Activity

24. TAIL SUSPENSION TEST

25. Purpose : To measure stress in rodents Principle : Behavioural test useful in the screening of potential anti-depressant drugs Procedure : Tail suspension boxes made of plastic with the dimensions (55 cm height X 60 cm width X 11.5 cm depth Control: Saline Standard: Diazepam(1mg/kg) Test: Drug to be Evaluated Adhere the tape to the tail of mice, suspend the animals by placing the free end of the tape on the suspension bar

26. Observe the activity after the administration of test drug Evaluation: The time that each test mice spends as mobile with comparision to control mice is measured Higher mobility : CNS Stimulant Lower mobility : CNS Depressant

27. TREAD WHEEL METHOD

28. Purpose : Effect of drug on locomotor activity of animal Principle : Based on the number of rotation of tread wheel on which animal moves Procedure : Wistar rats of either sex weighing 250-300 gm are grouped Control: Saline Standard: Methamphetamine(2mg/kg) Test: Drug to be Evaluated Animal placed in tread wheel for 10 min to observe activity changes

29. Evaluation: Changes in the movement (speed of rotation) of animal is measured Higher number of rotation : CNS Stimulant Lower number of rotation : CNS Depressant

30. ROTA-ROD TEST

31. Purpose : To evaluate the effect of drug on motor Principle : The length of time that a given animal stays on the rotating rod is a measure of their balance, co-ordination& physical condition Procedure : Mice weighing 18-24 gm are grouped Control: Saline Standard: Amphetamine(4mg/kg I.P) Test: Drug to be Evaluated After 30 min of administration animal placed on Rota-rod and observe activity of mice

32. Evaluation: The time for falling of animal is recorded More time : CNS Stimulant Less time : CNS Depressant

33. THANK YOU