Fidaxomicin is a macrolide antibiotic, which has a novel mechanism of action, mainly by inhibiting the RNA polymerase of bacteria to produce rapid anti-Clostridium difficile infection (CDI). Its treatment of CDI is superior to existing drugs. The safety and efficacy of Fidaxomicin were validated in two large, multicenter, randomized, double-blind, controlled clinical trials. Common adverse reactions of fedamycin include nausea, vomiting, headache, stomachache and dysentery.

Drug interaction

Fidaxomicin and its major metabolite, OP-1118, are substrates for P-glycoprotein efflux transporters, which are present in the GI tract. The interactions of fedamicin with P-glycoprotein substrates and their inhibitors, as well as with CYP450 isoenzymes 3A4, 2C9, and 2C19 have been evaluated. The drugs studied included cyclosporin, digoxin, midazolam, omeprazole and warfarin. Although the combination of cyclosporine and fedamicin nearly tripled the maximum blood concentration of Fidaxomicin, these changes were not clinically significant because the concentration was still in the ng/mL range. There was no change in the pharmacokinetics of Fidaxomicin in combination with the other drugs. According to current research, Fidaxomicin does not need to be adjusted when drugs that alter P-glycoprotein efflux transporters and cytochrome P450 isoenzymes are used simultaneously.