Alfaxalone

Alfaxalone

Clinical data
AHFS/Drugs.com	International Drug Names
ATC code	N01AX05 (WHO)
Legal status
Legal status	US: Schedule IV
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.
Identifiers
IUPAC name 3α-hydroxy-5α-pregnane-11,20-dione
CAS Number	23930-19-0 N
PubChem CID	104845
IUPHAR/BPS	5461
ChemSpider	94637 Y
UNII	BD07M97B2A
KEGG	D07282 Y
ChEMBL	CHEMBL190279 Y
ECHA InfoCard	100.164.405
Chemical and physical data
Formula	C21H32O3
Molar mass	332.477 g/mol
3D model (Jmol)	Interactive image
SMILES O=C2[C@H]3[C@H]([C@@H]1CC[C@H](C(=O)C)[C@@]1(C)C2)CC[C@H]4C[C@H](O)CC[C@]34C
InChI InChI=1S/C21H32O3/c1-12(22)16-6-7-17-15-5-4-13-10-14(23)8-9-20(13,2)19(15)18(24)11-21(16,17)3/h13-17,19,23H,4-11H2,1-3H3/t13-,14+,15-,16+,17-,19+,20-,21+/m0/s1 Y Key:DUHUCHOQIDJXAT-OLVMNOGESA-N Y
NY (what is this?)

Alfaxalone (INN, JAN), also known as alphaxalone or alphaxolone (BAN), is a neuroactive steroid and general anaesthetic. It is used in veterinary practice under the trade name Alfaxan, 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 GABA_A cell surface receptors.

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

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