Rectal ketamine for induction of anaesthesia in children.

Rectal premedication with atropine and diazepam and rectal induction of anaesthesia with ketamine have been used in 30 healthy children undergoing minor surgery. The anticholinergic and sedative effects of the premedication were satisfactory. Induction of anaesthesia was smooth with no adverse circulatory or respiratory effects. No psychotomimetic side-effects were seen, and analgesia persisted into the recovery period. Plasma concentrations of ketamine and norketamine were measured in eight children and revealed a pharmacokinetic pattern indicating comparatively low bioavailability probably due to incomplete absorption from the rectum and a high 'first-pass' metabolism. The technique of rectal administration of ketamine needs further pharmacokinetic evaluation before it can be generally recommended.