Indications: sole anesthetic for surgical procedure for two or more hours. For the induction of anesthesia prior to the administration of other general anesthetic agents. Used to supplement low potency agents such as nitrous oxide.

Cautions: hypertension, eclampsia, convulsions, psychiatric diseases.

Contra-indications: in patients with hypertension and is best avoided in those prone to hallucinations or nightmares; porphyria.

Side Effects: cardiovascular stimulation, tachycardia, and raised arterial pressure high incidence of hallucinations, nightmares, and other transient psychotic effects.

Drug Interactions: barbiturates, diazepam, hydroxyzine, tubocurarine.

Dose: By intramuscular injection, short procedures, initially 6.5–13 mg/kg (10 mg/kg usually produces 12–25 minutes of surgical anaesthesia)

Diagnostic manoeuvres and procedures not involving intense pain, initially 4 mg/kg.

By intravenous injection over at least 60 seconds, short procedures, initially 1–4.5 mg/kg (2 mg/kg usually produces 5–10 minutes of surgical anaesthesia).

By intravenous infusion of a solution containing 1 mg/ml, longer procedures, induction, total dose of 0.5–2 mg/kg; maintenance, 10–45 mcg/kg/minute, rate adjusted according to response.