All of the following cause inhibition of CYP3A except.: (A) Saquinavir, (B) Ritonavir, (C) Itraconazole, (D) Erythromycin
Answer is A. Ans. (A) Saquinavir(Ref: Katzung 11th/e p58, 863)All the drugs given in the options are microsomal enzyme inhibitors. Among protease inhibitors, ritonavir is the strongest inhibitor of CYP3A4 enzymes whereas saquinavir is the weakest.