Overview
Thiopental (thiopental sodium) is an ultra-short-acting barbiturate anesthetic agent used primarily for induction of general anesthesia and for the management of increased intracranial pressure. It produces rapid onset of anesthesia (within 30-60 seconds) with short duration of action (5-10 minutes) due to rapid redistribution from the brain to peripheral tissues.
Mechanism of Action
Thiopental acts primarily as a GABA-A receptor agonist, enhancing the inhibitory effects of GABA in the central nervous system. It increases the duration of chloride channel opening at GABA receptors, leading to neuronal hyperpolarization and CNS depression. It also decreases cerebral metabolic rate and cerebral blood flow.
Indications
- Induction of general anesthesia
- Adjunct in balanced anesthesia
- Control of convulsive states
- Reduction of increased intracranial pressure
- Cerebral protection during neurosurgical procedures
Dosage
For anesthesia induction: Adults: 3-5 mg/kg IV (usual range 2-4.5 mg/kg). Children: 5-6 mg/kg IV. For intracranial pressure reduction: 1.5-3.5 mg/kg IV loading dose followed by continuous infusion of 0.5-3 mg/kg/hour. Administer IV slowly over 20-30 seconds.
Black Box Warning
Warning: Intra-arterial injection may cause severe necrosis and gangrene requiring amputation. Ensure proper intravenous placement before administration.
Contraindications
- Hypersensitivity to barbiturates
- Acute intermittent porphyria
- Severe hepatic impairment
- Severe respiratory depression
- Status asthmaticus
- Severe cardiovascular instability
Side Effects
- Respiratory depression
- Hypotension
- Myocardial depression
- Laryngospasm
- Bronchospasm
- Nausea and vomiting
- Hiccups
- Shivering
- Emergence delirium
- Pain at injection site
- Thrombophlebitis
Interactions
- Enhanced CNS depression with other CNS depressants (alcohol, opioids, benzodiazepines)
- Reduced effectiveness of oral anticoagulants
- Decreased metabolism of other drugs metabolized by hepatic enzymes
- Increased risk of hypotension with antihypertensive agents
- Possible reduced effectiveness of oral contraceptives