Indications: analgesia; adjunct to general anesthetics; anesthetic for induction and maintenance; neuroleptanalgesia if given with a neuroleptic.

Cautions: elderly and debilitated patients; respiratory depression; concomitant administration with opioid premedications and other CNS - depressant drugs: pregnancy; lactating mothers.

Contra-indications: avoid in acute respiratory depression, acute alcoholism and where risk of paralytic ileus; also avoid in raised intracranial pressure or head injury (affects pupillary responses vital for neurological assessment); avoid injection in phaeochromocytoma (risk of pressor response to histamine release).

Side Effects: respiratory depression; muscular rigidity; hypotension; bradycardia; laryngospasm; nausea and vomiting.

Dose: as analgesic supplement to general anesthesia, low dose 2mcg/kg body weight. In painful minor surgery, 2-20 mcg/kg body weight; In complicated surgery, 20-50 mcg/kg body weight. Supplemental dose of 25-250 mcg may be added according to the needs of the patient and length of surgery. Child, 2-12 years, for induction and maintenance, 2-3 mcg/kg body weight.