1. CNS Depressant Drugs 322 PHL Lab # 4
King Saud University College Of Pharmacy Department of Pharmacology
CNS Depressant Drugs
322 PHL
Lab # 4

2. Classification of CNS Depressant Drugs According to Their Pharmacological action
1- Sedative – hypnotics 2- Tranquillizers 3- Anesthetics

3. General signs for CNS depressants
1- ↓ vitality 2- ↓ excitability 3- ↓ HR & RR

4. I. Sedative – hypnotics
Sedatives: Drugs which calm the patient & cause sedation and in large doses they induce sleeping. Hypnotics: Drugs which induce sleep that resembles to the natural sleep e.g. Barbiturates

5. Natural Sleep
Sleep: Physiological depression of consciousness. Sleep cycle: Starts with latency period → NREM → REM → cycles of NREM alternate with REM (about 4 cycles)

6. Natural Sleep REM NREM Rapid eye movement.
Consist of one stage (dreaming stage).
Lasts for 20 min.
Dreaming .
Non rapid eye movement.
Consist of 4 stages.
Lasts for 90 min.
Thinking.

7. II- Tranquillizers Definition:
Tranquillizers are drugs which relief mental anxiety & stress without affecting the consciousness.
e.g. Chlorpromazine (CPZ)
MOA:
It is D2 , 5-HT , H1, α1 antagonist

8. III- Anesthetics
Definition: Drugs which cause unconsciousness & generalized loss of pain sensation, thus allow surgical procedures to be carried out . e.g. thiopental (IV) , halothane (inhalation) MOA: Interfering with propagation of nerve impulses by interfering with electrolytes conductance through the cell membrane.

9. Sedative – hypnotics: Classification
Barbiturates
1-Long acting (12-24 hr)
e.g. Phenobarbital
2-Intermediate acting (8-12hr)
e.g. Amobarbital
3-Short acting (4-8 hr)
e.g. Pentobarbital
4-Ultrashort acting (0.5-1 hr)
e.g. Thiopental
Non-barbiturates
Benzodiazepines
Non- benzodiazepine

10. 1- Barbiturates MOA: They have GABA like action
(They facilitating the GABA action → mediate opening of chloride channels →increase CL influx → hyperpolarization
Classification according to their duration of action:
1-Long-acting .
2-Intermediate-acting .
3-Short acting .
4-Ultrashort acting .

11. 2- Benzodiazepines
Benzodiazepines enhance the response to GABAa by facilitating the opening of GABA-activated chloride channels

12. 2- Benzodiazepines
They bind specifically to a regulatory site of the receptor, distinct from the GABA-binding site, and act allosterically to increase the affinity of GABA for the receptor
e.g.
Diazepam (sedative)
(Triazolam (hypnotic

13. 3- Non-barbiturate Non-BZD
(5-HTA1) agonist e.g. buspirone.
Chloral hydrate (prodrug) converted to trichloroethanol.
Antihistamine e.g. diphenhydramine.
Paraldehyde .
Promethazine .

14. Specific signs of sedative-hypnotic
Drugs: Thiopental, Phenobarbital & chloral hydrate . Signs: 1- Staggering gait . 2- Sleeping posture . 3- Loss of righting reflex (onset time) . 4- ↓ Touch & pain reflexes ( lost with thiopental ) .

15. Specific signs for CBZ
Signs: 1- No loss of righting reflex . 2- Creeping gait. 3- Abdomen touches the ground. 4- State of catalepsy (loss of muscles control)→(onset time) 5- ↓ Touch & pain reflexes.

16. Lab work ROA Dose Conc. Drug IP 100 mg/kg 2.5 % 200 mg/kg 2% 300 mg/kg
Thiopental
200 mg/kg 2%
phenobarbital
300 mg/kg
3 %
Chloralhydrate
15 mg/kg
0.1%
C.P.Z