About Ketoconazole Imidazole derivative, A broad spectrum Antifungal. Mechanism of Action of Ketoconazole Ketoconazole is fungicidal or fungistatic depending on concentrations. I t inhibits the conversion of Lanosterol to 14 demethyl Lanosterol by inhibiting the cytochromeP450 enzyme 14 alpha demethylase and impair ergosterol synthesis. This will alter cell membrane and its permeability. This will results in loss of intracellular components. It also inhibits biosynthesis of triglycerides and phospholipids by fungi. It also inhibits several enzymes (e.g. Oxidative and peroxidative enzymes) which are involved in detoxification process. This will leads to cellular necrosis. Interactions for Ketoconazole Antacids & Histamine H2 antagonists: Increased gastric pH may inhibit ketoconazole absorption. Isoniazid: The bioavailability of Ketoconazole may be decreased. Rifampicin: Decreased serum levels of either drug may occur.