Article: New Antibiotic for C. Diff Ignites Discussion

By Rosemary Frei, MSc

Fidaxomicin (Dificid, Optimer Pharmaceuticals, Inc., and Cubist Pharmaceuticals, Inc.) is a new entrant into the thin field of agents that fight Clostridium difficile infection (CDI). Will the first antibiotic approved to treat CDI in the past 30 years live up to the promise set forth by its unanimous FDA approval? The health care community hopes it will, particularly because C. difficile is one of the top infection-causing pathogens in the United States, according to the Centers for Disease Control and Prevention.

When the FDA’s Anti-Infective Drugs Advisory Committee (AIDAC) met on April 5, the vote on the question of whether Optimer Pharmaceuticals had demonstrated the safety and efficacy of fidaxomicin was unequivocal: All 13 committee members voted yes. Acting on the advice of the AIDAC, the FDA approved fidaxomicin on May 27 for the treatment of C. difficile-associated diarrhea (CDAD) in adults aged 18 years and older.

A few days after the approval, on May 31, Optimer and Cubist, which are co-promoting the drug in the United States, announced that they will charge $2,800 for a 10-day course of fidaxomicin. The price—which is higher than that of its only serious competitor, vancomycin (Vancocin, ViroPharma Incorporated)—reflects the fact that the debutante has a higher rate of sustained clinical response at 25 days post-therapy and that vancomycin is dosed more frequently.

“Vancomycin costs around $1,700 to $2,000 at the doses currently used, and so the price of fidaxomicin may be appropriate.Â" said Glenn Tillotson, PhD, Optimer’s senior vice president of medical affairs.

Christina Surawicz, MD, professor of medicine in the Division of Gastroenterology, University of Washington School of Medicine, Seattle, was a member of the FDA’s AIDAC. She believes the arrival of fidaxomicin on the market is “excitingÂ" but that the high cost of the drug may be a barrier to its use.

“It’s promising that the recurrence rate is lower with fidaxomicin than with vancomycin, but at this time that doesn’t translate into knowing that there is efficacy in treating recurrences,Â" said Dr. Surawicz.