Seminar M.Pharm Sem 2nd

1. Hypnotics
Screening Methods
By Tarun Biswas
M.Pharm Sem.II
Dept. of Pharmacology
Guided By Mr.Rupesh Gautam
Sr.Lecturer in Pharmacology
Jaipur College of Pharmacy
Rajasthan, India

2. • Hypnotic:- Hypnotic drug are that
which induce and / or maintain sleep,
similar to normal arousable sleep.

3. Screening Methods
1. Potentiation of hexobarbital sleeping
time
2. Experimental insomnia in rats
3. EEG registration in conscious cats
4. Automated rat sleep analysis system

4. 1.Pontentiation of hexobarbital
sleeping time
principle:-
. The test is used to elucidate CNS activity of
drugs
. Not only hypnotics, sedative, tranquilizers but
also antidepressants
. The loss of righting reflex is measured for the
duration of hexobarbital sleeping time
. Mice are used in this test.

5. Procedure cont ….
• NMRI mice(male) in group of 10
• Average weight - 18-22gm
• Orally, i.p. or s.c. dosage of test or standard
compound (e.g. Diazepam 3 mg/kg) or the
vehicle.
• After 30 min i.p. or s.c injection or 60 min after
oral dosing 60 mg/kg hexobarbital is injected
i.v route

6. Procedure cont ….
• The animals are placed on their backs on a
warmed (37 C) pad and the duration of loss of
righting reflex( starting time of hexobarbital
injection) is measured.
• Injection of hexobarbital usually cause
anesthesia for about 15 min.

7. Evaluation:-
• Mean value of duration of anesthesia are
recorded in control and experimental
group
• % change in duration of anesthesia is
calculated

8. 2.Experimental insomnia in rats
• Developed by james and piper 1978
• The compounds are tested in normal
animals where they do not significantly
decrease weakfulness.
Procedure:-
• Male wistar rate 200-275gm prepared for
chronic electroencephalographic and
electomyographic recording.

9. 2.Experimental insomnia in rats
Cont.
• Four silver/silver chloride electrode and
two disc nuchal electrode are implanted
• Minimum10days allowed for recovery
from surgery
• Animals are placed into sound-
attenuated recording chamber with grid
floor.

10. Procedure cont….
• On the control day, the animals are dosed
with the vehicle and control nonstress
recording is obtained for 8hrs.
• Next day the animals are again injected
and then exposed to electric footshock for
8hrs
• The footshock is delivered through grid
floor of the recording chamber

11. Cont….
• During the footshock the EEG and EMG
recording circuits are automatically
interrupted
• On the next day the rats are dosed with the
test compound or the standard and
recording are obtained during a shock
session of 8hrs

12. Evaluation
• The sleep wake cycle is definitely altered
by the stress procedure .
• The amount of arousal and of slow wave
sleep 1 are increased .
• Slow wave 2nd and paradoxical sleep
decreased.
• Phenobarbitone and benzodiazepines
antagonize these change at least partially.

13. 3. EEG REGISTRATION IN CONSCIOUS
CATS
Principle
The effect of hypnotics on sleep pattern of
EEG tracings can be studied in conscious,
freely moving cats with chronically
implanted electrode

14. Procedure
• Female cats weighing 2.5-3.5 kg are
anesthetized and prepared with bipolar
subcortical electrodes in the reticular
formation,dorsal hippocampus,and
either amygdala,caudate necleus

15. Procedure cont….
• Cortical screw electrode are placed over
the anterior suprasylvian,lateral,medial
suprasylvian ectosylvian gyri
• Two teflon coated steel wires are placed in
the cervical neck muscles
All wires are connected to a subminiature
socket and implanted in dental acrylic

16. Cont….
• Cats of this chronic colony are then
intermittently utilized for drug experiments
at interdrug intervals of at least two weeks
• Cats are taken into an experimental
chamber 70, 80 cm high
• The box is lighted and ventilated with
room air at 21 c

17. Cont….
• The cat is immediately connected to a
cable which exits through the top center
of the cage into a mercury swivel
• Recording of the cortical EEG, cervical
neck muscle tone and reticular formation
multiple unit activity

18. Evaluation
• The data are analyzed by analysis of
variance with subjects, days , and
drug as factors

19. References
• Vogel. H. G, “Drug Discovery and
Evaluation” second edition, page no.495-
499