A comparison of the efficacy of detornidine by sublingual and intramuscular administration in ponies

Abstract

Preliminary trials established that, whilst detomidine is ineffective if given by stomach tube and is of variable efficacy in food, it can give effective sedation when administered by the sublingual route. A comparison was made in four ponies of the behavioural effects, and the effects on heart rate of detomidine at three dose rates (20, 40 and 80 μg/kg) given either by intramuscular injection or sublingually by squirting the drug under the tongue. Sedation was assessed by measuring the lowering of the ponies' heads and by scoring their responses to a variety of imposed stimuli. Ponies became sedated following detomidine administration at all doses and by all routes. The lowering of the head induced by detomidine was significantly influenced by the dose of drug and by the route of administration. For either route, higher doses produced the greatest effect. There was a significant correlation between the effects produced by the two routes of administration, the lowering of the head following sublingual administration being approximately threequarters of that after the same dose given intramuscularly. Onset of sedation was achieved more rapidly following intramuscular dosing than after sublingual administration. Falls in heart rate were similar after all drug administrations, but bradycardia was never profound. Subsequent clinical experience has proved that, providing adequate time (45 minutes) is allowed for maximal effects, sublingual administration of detomidine (40 μg/kg) can give a useful degree of sedation in horses which are difficult to inject.