Pharmacokinetics and effects of i.m. alfentanil as premedication for day-case ophthalmic surgery in elderly patients.

We have studied the pharmacokinetics and effects of i.m. alfentanil as premedication for peribulbar block in 90 patients undergoing elective day-case cataract surgery. We compared alfentanil 12.5 micrograms kg-1 injected into the deltoid (n = 30) or gluteal muscle (n = 30) 15 min before the peribulbar block, and placebo (n = 30). The alfentanil concentrations were significantly greater in the deltoid group during the study and the mean peak concentration occurred more rapidly in this group. Only alfentanil injected into the deltoid muscle reduced pain (assessed with a visual analogue scale (VAS)) associated with the peribulbar block. A mild sedative effect (VAS) was found in both alfentanil groups. We conclude that i.m. alfentanil appears to be a suitable premedicant for short, painful procedures because it has a short duration of action and is not associated with any clinically significant side effects.