Awatif B. Al-Backer

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

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

Awatif B. Al-Backer I. Sedative – hypnotics Definitions Sedatives: Drugs which calm the patient & cause sedation and in large doses causing sleep Hypnotics: Drugs which induce sleep that resembles the natural sleep Ex. Barbiturates

Awatif B. Al-Backer SleepDefinition: Physiological depression of consciousness Sleep cycle: ) Starts with latency period → NREM → REM → cycles of NREM alternate with REM (about 4 cycles)NREM REM REM - Non rapid eye movement - Lasts for 90 min. - Thinking - Rapid eye movement - Lasts for 20 min. - Dreaming

Awatif B. Al-Backer II- Tranquillizers Definition: Tranquillizers are drugs which relief mental anxiety & stress without affecting the consciousness Ex. Chlorpromazine (CPZ)

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

Awatif B. Al-Backer Sedative – hypnotics: Classification Sedative-hypnotics Barbiturates 1-Long acting (12-24 hr) Ex. Phenobarbital 2-Intermediate acting (8-12hr) Ex. Amobarbital 3-Short acting (4-8 hr) Ex. Pentobarbital 4-Ultrashort acting (0.5- 1hr) Ex. Thiopental Non-barbiturates BenzodiazepinesNon- benzodiazepine

Awatif B. Al-Backer 1- Barbiturates MOA: They have GABA like action → ↑ opening time of chloride channels → ↑conductance of chloride ions → hyperpolarization Classification according to their duration of action: 1-Long-acting 2-Intermediate-acting 3-Short acting 4-Ultrashort acting

Awatif B. Al-Backer 2- Benzodiazepines MOA: Bind non-selectively to BZD receptors omega1 (GABA- dependant) & omega2. ‡ omega1 → ‡ GABA receptors Gi protein → ↓cAMP → Gi protein → ↓cAMP → relaxation relaxationEx. - - Diazepam (sedative) - Triazolam (hypnotic) chloride dependant →hyperpolarization

Awatif B. Al-Backer 3- Non-barbiturate Non-BZD 1- 5-HT agonist e.g. buspirone (5-HTA1) 2- Chloral hydrate (prodrug) converted to trichloroethanol 3- Antihistamine e.g. diphenhydramine 4- Paraldehyde 5- Promethazine

Awatif B. Al-Backer 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)

Awatif B. Al-Backer 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

Awatif B. Al-Backer Lab work DrugConc. Dose ROA Thiopental 2.5 % 100 mg/kg IP Strychnine 2 % 200 mg/kg IP Chloralhydrate 3 % 300 mg/kg C.P.Z 0.1% 15 mg/kg IP

Awatif B. Al-Backer