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Created Feb 2019 | Updated Nov 2020




DEA CODE 2731: Schedule 4

Alfaxalone is a rapidly acting hydrophobic synthetic neurosteroid. It is indicated for the induction and maintenance of anesthesia and for induction of anesthesia followed by maintenance with an inhalant anesthetic, in cats and dogs. 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). 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. Alfaxalone can be safely combined with premedicants (xylazine, (dex)medetomidine, acepromazine, midazolam), opioids (morphine, methadone, hydromorphone, butorphanol, nalbuphine, buprenorphine, fentanyl), and NSAIDs. Alfaxalone's adverse reactions are: hypotension, tachycardia, apnea, hypertension, bradypnea and others.

For veterinary use.
ALFAXAN (alfaxalone) is a neuroactive steroid molecule with properties of a general anesthetic. ALFAXAN is indicated for the induction and maintenance of anesthesia and for induction of anesthesia followed by maintenance with an inhalant anesthetic, in cats and dogs.

Not for human use. Keep out of the reach of children.

Alfaxalone is a central nervous system depressant that acts on GABA receptor associated chloride channels, similar to the mechanism of action of Schedule IV sedatives such as benzodiazepines (diazepam and midazolam), barbiturates (phenobarbital and methohexital) and fospropofol.

Alfaxalone was marketed in 1971 in combination with alfadolone acetate under the brand name Althesin for human use and Saffan for veterinary use. Althesin was withdrawn from the market in 1984, whereas Saffan remained marketed. A new formulation containing alfaxalone only was introduced for veterinary use in 1999 under the brand name Alfaxan. Following the introduction of Alfaxan, Saffan was gradually discontinued and is now no longer marketed. Another new formulation containing alfaxalone alone is currently under development for use in humans with the tentative brand name Phaxan

  • A neuroactive steroid and general anesthetic
  • Used currently in veterinary practice as an induction agent for anesthesia and as an injectable anesthetic. Alfaxalone causes the animal to relax enough to be intubated, which then allows the administration of inhalational anesthesia.
  • Though it is more expensive than other induction agents, it often preferred due to the lack of depressive effects on the cardiovascular system.
  • It is cleared quickly by the liver, giving it a relatively short terminal half-life and preventing it from accumulating in the body, lowering the chance of overdose.
  • Currently, a human form of alfaxalone is in development under the name Phaxan

The most common side effect seen in current veterinary practice is respiratory depression when Alfaxan is administered concurrently with other sedative and anesthetic drugs; when premedications aren't given, veterinary patients also become agitated and hypersensitive when waking up.

Despite its use as an anesthetic, alfaxalone itself has no analgesic properties

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