Thiopental

• •IV induction (largely historical/limited availability in US)
• •Neuroprotection/burst suppression
• •Status epilepticus (refractory)

Onset ~30 sec (arm–brain). Short duration by REDISTRIBUTION (not metabolism); context-sensitive half-time rises sharply with infusion (zero-order kinetics at high dose).

↓ BP (venodilation + myocardial depression), compensatory tachycardia. Dose-dependent.

Dose-dependent respiratory depression/apnea.

• !Hypotension
• !Laryngospasm/bronchospasm (light plane)
• !Tissue necrosis if extravasated; intra-arterial injection → severe vasospasm/gangrene
• !Precipitates porphyria (ALA synthase induction)

• ×Acute intermittent porphyria (ABSOLUTE)
• ×Status asthmaticus (relative)
• ×Hemodynamic instability

• ★ACUTE PORPHYRIA is an absolute contraindication (barbiturates induce ALA synthase).
• ★Wake-up after a single dose is by redistribution — repeated dosing/infusion accumulates (long context-sensitive half-time).
• ★Intra-arterial injection is a surgical emergency (crystallization → vasospasm/thrombosis).

• Propofol

  Potentiates GABA-A chloride conductance. Direct CNS depression with no analgesia.

• Etomidate

  GABA-A potentiation. Highly hemodynamically stable due to minimal SVR/contractility effects.

• Ketamine

  Non-competitive NMDA receptor antagonist. Also effects on opioid, monoaminergic, muscarinic receptors. Produces dissociative anesthesia with analgesia.

• Methohexital

  GABA-A potentiation. Shorter-acting than thiopental; lowers seizure threshold (useful for ECT).

• Remimazolam

  GABA-A benzodiazepine agonist with an ester linkage → rapid hydrolysis by tissue esterases (like remifentanil among opioids) → fast recovery, organ-independent.

Browse all classes: /reference/drugs

• •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
• •Miller's Anesthesia, 9e
• •FDA package insert