Abstract

Desethylamiodarone was reported to inactivate human CYP1A1. To assess this, two protocols were implemented employing dilution and non-dilution of the preincubation mixture. Inactivation studies performed with diluted preincubation mixtures showed no inactivation of CYP1A1 by desethylamiodarone. However there was evidence for a mixed competitive inhibition (competitive and the uncompetitive inhibition constants of 2.1 μM and 9.6 μM, respectively) of CYP1A1 by desethylamiodarone. NADPH addition and/or replenishment were found to be important factors in determining the control activity in inactivation studies.

Keywords: Desethylamiodarone, CYP1A1, metabolism, mechanism-based inhibition, inactivation, NADPH