Anesthesia
Barbiturates
- Primary Use: Induction of anesthesia
- Mechanism of Action: Facilitate inhibitory neurotransmission by enhancing GABAA receptor function.
- Pharmacokinetics: Metabolism and elimination are hepatic. Multiple doses or prolonged infusions may produce prolonged sedation or unconsciousness.
- Pharmacodynamics:
- CNS: Dose-dependent CNS depression. ↓ in (CMRO2) cause ↓ in ICP and (CBF).
- Cardiovascular System: Depress myocardial contractility, leading to dose-dependent ↓ in BP.
- Respiratory System: Laryngeal reflexes remain more intact compared to propofol so higher incidence of cough and laryngospasm. Dose-dependent histamine release. Contraindicated in asthmatic patients.
- Advantages:
- Rapid onset & short duration due to redistribution from brain to muscle resulting in return of consciousness.
- Potent anticonvulsant properties.
Therapeutics
It accelerates T4 breakdown (by hepatic enzyme induction).
It may be helpful both as sedative and to decrease T4 level.
Treatment of convulsion if patient present in crisis. Adequate vitamins and nutrition are essential due to the catabolic effect of thyroxin.