Priclinical screening tests are conducted on animal subjects to evaluate the pharmacological activity, toxicity, and effects of new CNS stimulant drugs prior to human testing. Some common screening tests include measuring drug-induced convulsions, locomotor activity in photoactometers, treadwheel activity, rotarod performance, sleep time after barbiturate administration, sand displacement ability, and running time in runways. The results of these animal behavior and function tests are used to initially assess if CNS stimulant drugs have their intended effects and what doses may be unsafe prior to progressing to clinical trials.

1. Priclinical screening of CNS stimulantes
Prepared by ;maheshdhanaboina
M.Pharmacy 1 sem
pharmacology

2.  Priclinical trail- a laboratory test of a new drug or a
series of chemicals, usually done on the animal subjects ,to see
if the hoped-treatment really works and if it is safe to test on
humans
 Screening of drugs;
• Get pharmacological activity of new/chemically
undefined substances
• Investigate functions of endogenous mediators
• Measure /define the toxicity and /or unwanted
actions

3.  Defination ;stimulants are the psychoactive drugs that
induce temporary improvement in either mental or
physicalfunction or both
 CNS stimulants may be defined as drug substance that
most spesically afford an enhancement in excitability
either verey much whith in the different portions of the
spinal cord which may lead to convolsion.

4. 1. Analeptics( convulsant)
• Doxapram
• Nikethamide
• Strychnine
• Picrotoxin
2 Psychomotor stimulants
• Amphetamine & methamphetamine
• Methylphenidate
• Cocaine
• phentamine

5. 3 General cellular stimulants
• Methyl xanthane darivatives
• Caffeine theophylline
• Theobromine
4 Clinical anti depressents
• MOA inhibitors
• Catacholamine reptake inhibitors

6. 1. Strychinie induced convulsion
2. Sand displacement method
3. Ranway test
4. Ptosis test
5. Duration of anaesthia
6. Jiggle cage method
7. Treadwheel method
8. Rotarod method
9. Barbiturate induced sleeping time

7.  Purpose; CNS stimulantes like ampthetamine
incress the locomotor activity in animal.
 procedure ; mice weighing 20-25 gm are
divided in into 3 groups ,each contain 4
animals
control ; saline
standard ; amphetamine(1mg/kg I p)
test ; drug to be evaluated

8. Mice from each group ,separately placed in
photoactometer for 10 min duration at the
intervals of 30 min till the maximum effect
of drug is observed.
• Evaluation; no. of ‘cut off ‘is compared
between groups.

9. • PROCEDURE ; groups 10mices of either sex with
a weight between 18 to 22 gm
• Mice are injected with 2 mg/kg strchninenitrate
.i.p in std group and in test group test drug is
given
• After few minutes convulsions are observed

10. o Evaluation ; time reuired to produce
convulsions' is compared
o Modifications ; some other drugs
produce same effects like picotoxin
pentyleneterazole

11. • Wister rates of either sex weighing 250-300
gm are grouped
• Control ; saline standard :methamphetamine
(2 mg/kg i.p)
• Test ; drug to be evaluated
• Animal placed in tread wheel for 10 min to
observe activity changes

12. • Evaluation ;changes in the movement (speed
of rotation) of animal.

13. 1. Mice weighing 18 -24gm are grouped
Control ; saline
Standard ; amphetamine(4mg/kg)
Test ; drug to be evaluated
After 30min Animal placedon rotarod

14.  Evaluation ; the time for falling of animal is
recorded

15. 1. Mice weighing 20 -30 gm are grouped
Control ; distilled water (10 ml/kg i.p)
standard ; caffeine (20 mg/kg s.c)
test ; drug to be evaluated
Afteer 30 min phentobarbitone (40 mg /kg i.p)

16. Animal are observed for onset and duration of
sleeping
• Evaluation ; the sleeping time
• the sleeping time is the time interval
between onset of righting and regin of
righting reflex.

17. Procedure ; a cage with sand is calibrated for
amount of sand displaced per unit time
mice weighing 20 -25 gm are devided in 3
groups
Control; saline
Standard ;caffeine
Test ; drug to be evaluated after 1 hour the
animal placed in cage for 15 min

18.  Evaluation ; volume of sand displaced in each
group is compared

19. Procedure ; wister rats of either sex weighing
250 – 300 gm are grouped
Trained to run in run way apparatus for 3 days
to achive constant time and speed to pass
runway
control; saline

20. Standard ; methamphetamine (2 mg/kg i.p)
Test ; drug to be evaluated
After 30 min of administration of drug test is
performed
Evaluation ; Running time from door opening
to pressing the goal was recorded using a
microcomputer