Porphyrinogenicity of etomidate and ketamine as continuous infusions. Screening in the DDC-primed rat model

The porphyrinogenicity of etomidate and ketamine administered as continuous i.v. infusions was screened in the DDC-primed rat model of latent variegate porphyria. Ketamine produced no change from control in 5-aminolaevulinate synthase (ALAs) activity and haem intermediate production in either untreated or DDC-primed rats, and would appear to be safe for use in the patient with genetic porphyria. Etomidate, while producing no significant changes in these parameters in untreated rats, caused a statistically significant 47% increase in hepatic ALAs activity with a corroborative 85% increase in coproporphyrin and a 40% increase in protoporphyrin content, in DDC-primed rats. On these grounds, etomidate must be regarded as potentially porphyrinogenic when administered as a continuous infusion for total i.v. anaesthesia.