Comparison of sedative effects of romifidine following intravenous, intramuscular, and sublingual administration to horses

Abstract

Abstract Objective To compare sedative effects of romifidine following IV, IM, or sublingual (SL) administration in horses. Animals 30 horses that required sedation for routine tooth rasping. Procedure Horses (n = 10/group) were given romifidine (120 μg/kg) IV, IM, or SL. Heart rate, respiratory rate, head height, distance between the ear tips, thickness of the upper lip, response to auditory stimulation, response to tactile stimulation, and degree of ataxia were recorded every 15 minutes for 180 minutes. Tooth rasping was performed 60 minutes after administration of romifidine, and overall adequacy of sedation was assessed. Results IV and IM administration of romifidine induced significant sedation, but SL administration did not induce significant sedative effects. Scores for overall adequacy of sedation after IV and IM sedation were not significantly different from each other but were significantly different from scores for horses given romifidine SL. Sedative and other effects varied among groups during the first 60 minutes after drug administration; thereafter, effects of IV and IM administration were similar. Conclusions and Clinical Relevance Onset of action was fastest and degree of sedation was greater after IV, compared with IM, administration of romifidine, but duration of action was longer after IM administration. Sublingual administration did not result in clinically important sedative effects. (Am J Vet Res 1999;60:954-959)