Azepexole, a potent alpha 2-agonist with anaesthetic effects, does not affect cerebral energy consumption in dogs given isoflurane.

The effects of the alpha 2-agonist azepexole on the cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) were studied by a sagittal sinus outflow technique in dogs. Azepexole, 1 mg kg-1 (reported to decrease the anaesthetic requirement for isoflurane by almost 90%), caused no change in CMRO2 when given during 1.4% isoflurane anaesthesia. CBF was reduced by 26%. When the concentration of isoflurane was reduced to 0.2%, CMRO2 increased by 26% as would have been expected for the change in isoflurane concentration alone. Concomitantly CBF increased to a level not significantly different from control. Azepexole might be a useful adjunct to inhalational anaesthetics, and combined with a low dose of isoflurane it should be an excellent background anaesthetic when studying the effect of other drugs on CMRO2 in dogs as the combination seems to have little effect on the CMRO2.