The objective of this study was to determine the pharmacodynamic effects in sheep of the anaesthetic alfaxalone in a 2-hydroxypropyl-β-cyclodextrin formulation. Seven Ripollesa sheep, weighing 43.0±6.6 kg, were used in the study. Twenty-four hours after instrumentation, the sheep were anesthetised with alfaxalone (2 mg/kg bodyweight IV) in cyclodextrin. Heart rate, arterial blood pressure, respiratory rate and arterial blood gases were recorded. Alfaxalone administration resulted in minimal cardio-respiratory depression. Time to standing from anaesthesia was 22.0±10.6 min. Apnoea was not observed in any of the sheep. Significant differences from baseline were not observed in respiratory rate or arterial blood pressure. Heart rate increased significantly (P<0.05) immediately after administration, returning to control values at 20 min. The calculated haemoglobin saturation (SO2) decreased significantly during the first 15 min after alfaxalone administration. The arterial pH decreased significantly during the first 30 min of the study, although no significant differences from basal values were observed in the arterial partial pressure of carbon dioxide (PaCO2). The results showed that alfaxalone in 2-hydroxypropyl-β-cyclodextrin administered as an IV bolus at 2 mg/kg produced minimal adverse effects and an uneventful recovery from anaesthesia in sheep.
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