Alfaxan is formulated with the active ingredient alfaxalone in an aqueous solution with a pH of 6.5-7 and is registered for the induction and maintenance of anaesthesia in dogs and cats and the induction of anaesthesia in pet rabbits. Download SPC.
Alfaxalone is a neuroactive steroid molecule, with central effects. Despite being an analogue of progesterone, alfaxalone does not bind to sex hormone, glucocorticoid, or mineralocorticoid receptors69.
Alfaxalone induces anaesthesia through activity at the gamma amino butyric acid sub-type A receptor (GABAA) present on cells in the Central Nervous System (CNS). GABA is a major inhibitory neurotransmitter in the CNS. Alfaxalone enhances the effects of GABA at the GABAA receptors resulting in opening of channels into the cells and an influx of chloride ions. This causes hyperpolarisation of the cells and inhibition of neural impulse transmission. 62, 68
Steroids were first recognised to have anaesthetic properties in the 1940s 66, 67. Numerous investigations and iterations of steroid molecular modification have occurred over time in the attempt to create useful formulations of neurosteroid molecules. 63, 64, 65
The first commercially manufactured formulation of neurosteroids was widely used through the 1970s and 1980s in both human and veterinary anaesthesia. Neurosteroid anaesthesia was recognised for its excellent anaesthetic properties and minimal effects on cardiovascular function. 60, 61
Alfaxan® in Pet Rabbits