Possible Interaction: Phenacetin and Quinidine

“Amiodarone, bepridil, aprindine, lignocaine, flecainide and quinidine inhibited phenacetin O-deethylation in a concentration-dependent manner, although the inhibitory effects were relatively weak with IC50 values ranging from 86 to 704 microM. Propafenone and mexiletine selectively abolished the high-affinity component of phenacetin O-deethylation in human liver microsomes.”

“Very much higher (1000-fold) levels of quinidine were required to inhibit the O-deethylation of phenacetin , being rather less potent in this than quinine.”