A comparison of the porphyrin-inducing activity of barbiturates and benzodiazepines in chick embryo liver cells.

Five benzodiazepines, flurazepam, nitrazepam, diazepam, oxazepam, and chlordiazepoxide, have been tested for porphyrin-inducing activity in chick embryo liver cell culture and for delta-aminolevulinic acid (ALA) synthetase inducing activity in the 17-day-old chick embryo. Flurazepam and nitrazepam were found to have considerably lower potency than secobarbital whereas diazepam, oxazepam, and chlordiazepoxide were less potent than phenobarbital in these test systems. The following conclusions were arrived at. (1) A hypnotic dose of flurazepam or nitrazepam would be less likely than a comparable dose of secobarbital to increase ALA synthetase activity in a patient with hereditary hepatic porphyria. (2) A sedative dose of diazepam, oxazepam, or chlordiazepoxide would be less likely than a comparable dose of phenobarbital to increase ALA synthetase activity in a patient with hereditary hepatic porphyria. (3) The benzodiazepines, although apparently less likely to precipitate an attack than barbiturates, should be used with great caution in porphyria patients.