Systematic (IUPAC) name
Clinical data
Legal status
Pharmacokinetic data
Bioavailability The alfaxalone molecule is solubilised using SBECD. Cyclodextrins are complex polysaccharides derived from starch that supply a hydrophobic centre for lipophilic drugs like alfaxalone.
CAS number  N
ATC code N01
ChemSpider  YesY
Chemical data
Formula C21H32O3 
Mol. mass 332.477 g/mol

Alfaxalone (INN, JAN), also known as alphaxalone or alphaxolone (BAN), is a neuroactive steroid and general anaesthetic.[1] It is used in veterinary practice under the trade name Alfaxan,[2] and is licensed for use in both dogs and cats. Along with alfadolone, it is also one of the constituents of anesthetic drug mixture althesin.

Unlike some of its predecessors alfaxalone is not associated with histamine release and anaphylaxis.

A study 1987 found the primary mechanism for the anaesthetic action of alfaxalone to be modulation of neuronal cell membrane chloride ion transport, induced by binding of alfaxalone to GABAA cell surface receptors. [3]

A 1994 study found that alfaxalone binds to a different region of this receptor than the benzodiazepines. .[4] These benzodiazepine-insensitive GABAA receptors are located extrasynaptically and are responsible for tonic inhibition. The occurrence of tonic GABAA inhibition coincides with the expression of relatively rare receptor subunits, articularly the α4, α6, and δ subunits, and as a general rule-of-thumb, δ subunit-containing receptors are extrasynaptic.[5]

Alfaxalone is metabolised rapidly in the liver. It has a very short plasma elimination half-life in dogs and cats.

See also


  1. ^ C.R. Ganellin; David J. Triggle (21 November 1996). Dictionary of Pharmacological Agents. CRC Press. pp. 1094–.  
  2. ^ "Alfaxalone". 
  3. ^ Harrison, N. L.; Vicini, S.; Barker, J. L. (1987). "A steroid anesthetic prolongs inhibitory postsynaptic currents in cultured rat hippocampal neurons" (pdf). The Journal of neuroscience 7 (2): 604–609.  
  4. ^ Mihic, S. J.; Whiting, P. J.; Klein, R. L.; Wafford, K. A.; Harris, R. A. (1994). "A single amino acid of the human gamma-aminobutyric acid type A receptor gamma 2 subunit determines benzodiazepine efficacy" (pdf). The Journal of Biological Chemistry 269 (52): 32768–32773.  
  5. ^ Wahab A, Heinemann U, Albus K (October 2009). "Effects of gamma-aminobutyric acid (GABA) agonists and a GABA uptake inhibitor on pharmacoresistant seizure like events in organotypic hippocampal slice cultures". Epilepsy Research 86 (2-3): 113–23. doi:10.1016/j.eplepsyres.2009.05.008. PMID 19535226.