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Althesin: a new intravenous steroid anaesthetic


The anaesthetic effects of pregnanedione and other related steroids were first described in 1941.1 Hydroxydione was the first drug in this group to be used clinically, but it had serious disadvantages.2 Althesin (Glaxo) is a mixture of two water-insoluble pregnanedione derivatives, alphaxalone and alphadolone, dissolved in Cremophor EL (polyoxyethylated castor oil), for intravenous injection. Alphaxalone is the major constituent; alpha-dolone is less potent and is put in to make alphaxalone more soluble in Cremophor. The solution is viscous, but slightly less so than that of propanidid (Epontol - Bayer), which also contains Cremophor.

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