DEXMEDETOMIDINE AS INTRAMUSCULAR PREMEDICATION FOR DAY-CASE CATARACT-SURGERY - A COMPARATIVE-STUDY OF DEXMEDETOMIDINE, MIDAZOLAM AND PLACEBO

The effects of dexmedetomidine 1.0 mu g.kg(-1), midazolam 20 mu g.kg(- 1) and saline placebo were assessed in a double-blind, randomised stud y in 90 patients undergoing day-case cataract surgery under regional a naesthesia. The trial drug was injected into the deltoid muscle 45 min before the peri-ocular block. Dexmedetomidine 1.0 mu g.kg(-1) decreas ed intra-ocular pressure before, during and after surgery. The maximum reduction in mean (SD) intra-ocular pressure occurred in the dexmedet omine group just before discharge from hospital (17.7 (2.8) mmHg to 11 .5 (2.9) mmHg) (p < 0.001 compared with midazolam and placebo). In con trast, midazolam did not differ from saline placebo. Dexmedetomidine a nd midazolam produced a similar sedative effect of short duration. Dex medetomidine induced a moderate decrease in blood pressure (p < 0.001 compared with placebo) and a slight but statistically significant decr ease in heart rate throughout the study period (p < 0.001 compared wit h placebo). Dexmedetomidine 1.0 mu g.kg(-1) intramuscularly, effective ly reduced intra-ocular pressure and produced short-acting sedation wi th marginal cardiovascular effects, it may be a useful premedicant dru g for elderly patients undergoing day-case cataract surgery under regi onal anaesthesia.