Screening of certain anaesthetic agents for their ability to elicit acute porphyric phases in susceptible patients.

The activity of delta-aminolaevulinic acid synthetase (E.C. 2.3.1.37) (ALA-S) was measured in rat liver after the simultaneous administration of various anesthetic agents and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) in vivo. Flunitrazepam, Althesin and phenobarbitone caused a significant increase in the activity of the enzyme which was not observed with propanidid, etomidate and minaxolone. It is suggested that DDC-treated rat, which resembles latent human variegate porphyria, may be a more valid method of testing drugs for their ability to elicit acute porphyric phases in susceptible individuals. The anaesthetic agents which induced the activity of hepatic ALA-S in this model are not recommended in patients with genetic hepatic porphyria.