Optimer antibiotic approved

Optimer Pharmaceuticals has won US Food and Drug Administration (FDA) approval for its orally delivered antibacterial drug Dificid (fidaxomicin) as a first-line treatment of Clostridium difficile-associated diarrhoea (CDAD) in adults 18 years of age and older.

C. difficile infections, which are characterised by diarrhoea and inflammation of the colon, are increasingly common in hospitals and other group care settings. CDAD, which can be life-threatening, is believed to affect at least 700,000 people in the US each year.

"In recent years, many in the infectious disease community have seen an increase in the number of cases of people with a C. difficile infection," said Dr Edward Cox, director of the Office of Antimicrobial Products in the FDA's Center for Drug Evaluation and Research. "Dificid is an effective new treatment option for patients who develop C. difficile-associated diarrhoea."

In clinical trials, Dificid worked as well as ViroPharma's Vancocin (vancomycin) in curing CDAD and was better than vancomycin at preventing recurrence of infection.

Dificid, which is Optimer's first approved product, could have global sales of about $203m a year, according to a consensus analyst forecast complied by Thomson Reuters. Fidaxomicin is the first in a new class of antibiotics called macrocycles, which inhibit the bacterial enzyme RNA polymerase. It is the only FDA-approved antibacterial drug proven to be superior to vancomycin in sustained clinical response for CDAD.

Under a two-year co-promotion deal signed last month, Cubist Pharmaceuticals will market Dificid in the US, with a launch planned for the third quarter of 2011. In Europe, where a marketing authorisation application for Dificid is pending with the European Medicines Agency, Optimer has partnered with Astellas Pharma Europe to commercialise the drug if it is approved.

Optimer will conduct several post-marketing studies, including a randomised clinical trial to evaluate the efficacy of the drug in the treatment of patients with multiple CDAD recurrences and two studies in paediatric patients. In addition, the company will conduct a post-market microbiological surveillance program to identify the potential for decreased susceptibility of C. difficile to fidaxomicin.