Miconazole interacts with 14-alpha demethylase, a cytochrome P450 enzyme necessary to convert lanosterol to ergosterol. As ergosterol is an essential component of the fungal cell membrane, inhibition of its synthesis results in increased cellular permeability causing leakage of cellular contents. Miconazol may also inhibit endogeneous respiration, interacts with membrane phospholipids, inhibit the transformation of yeast to mycelia forms, inhibit purine uptake and impaired triglyceride and phospholipid biosynthesis.
Reference: Tripathi K.D; Essentials of Clinical Pharmacology; Jaypee Brothers Medical Publishers; Seventh edition; Page no. 787, 792