Evaluation of the actions and use of alphaxolone/alphadolone (CT1341) in sheep

CT1341 (alphaxolone/alphadolone) (Saffan; Glaxo) at various dose rates was investigated for use as an intravenous anaesthetic agent in sheep and it was found that at least 1.65 mg/kg was required to induce anaesthesia. In an experimental group of animals the effect of CT1341 2.2 mg/kg, on PaO2, PaCO2, paH and mean arterial blood pressure was measured. The drug caused a mild respiratory acidosis accompanied by a slight decrease in PaCO2 tensions. Mean arterial blood pressure decreased by 50 per cent, 30 seconds after injection but this fall lasted for only 10 minutes. Prior administration of either atropine sulphate or mepyramine maleate failed to modify this hypotensive effect. Injection of the vehicle, Cremophor EL, alone had no effect on mean arterial blood pressure. Intracerebroventricular administration of CT1341 while producing anaesthesia failed to produce any hypotension. The drug was used for the induction of anaesthesia in 19 sheep. A mean dose of 3.0 mg/kg was found to be most useful clinically. In a further three sheep an infusion of a dilute solution (0.234 mg/kg per minute) was used to maintain anaesthesia. The most notable clinical feature in sheep was the fast, complete recovery. It is concluded that this agent is an extremely useful drug for the induction and maintenance of anaesthesia in sheep.