Indications: analgesia during and after operation, enhancement of anesthesia; pre-operative sedation.

Cautions: in head injuries with increased intracranial pressure; in patients with chronic respiratory insufficiency.

Contra-indications: avoid in acute respiratory depression, acute alcoholism and where risk of paralytic ileus; avoid injection in pheochromocytoma.

Side Effects: nausea and vomiting (particularly in initial stages), constipation, and drowsiness; larger doses produce respiratory depression, hypotension, and muscle rigidity; other side effects: include difficulty with micturition, ureteric or biliary spasm, dry mouth, sweating, headache, facial flushing, vertigo, bradycardia, tachycardia, palpitation, postural hypotension, hypothermia, hallucinations, dysphoria, mood changes, dependence, miosis, decreased libido or potency, rashes, urticaria and pruritus.

Dose: SC or IM injection, up to 10 mg 1-1.5 hours before operation.

Child, by IM injection, 150 mcg/kg.