Michele G. Sullivan is with the Mid-Atlantic bureau of Elsevier Global Medical News.
CHICAGO — An investigational antibiotic was just as effective as vancomycin in curing Clostridium difficile infection, with a significantly lower recurrence rate, in a phase III trial.
Mark Miller, MD, reported at the annual Digestive Disease Week that a 10-day course of fidaxomicin achieved a global cure (symptomatic cure plus no recurrence) in 78% of patients who took it. In comparison, the global cure rate was 67% in patients who took vancomycin, he said.
Fidaxomicin is being developed by Optimer Pharmaceuticals Inc.; the company also sponsored the trial. It is a macrocytic antibiotic, which works by inhibiting bacterial RNA polymerase, according to information on the company Web site.
The trial included 629 patients (mean age 61 years) with C. difficile infections. They reported a mean of nine unformed bowel movements per day; 6% were inpatients, and 6% had failed a course of metronidazole.
Patients were randomized to 10 days of either fidaxomicin 200 mg twice a day, or vancomycin 125 mg 4 times per day. The primary end point was resolution of symptoms and no need for additional therapy for 2 days after stopping the study drug. The secondary endpoints were recurrence and global cure.
The per-protocol analysis included 548 patients. Cure rates were not significantly different between the treatment groups, at 92% for fidaxomicin and 90% for vancomycin. However, recurrence rates were significantly lower in the fidaxomicin group (13% vs. 24%, respectively). Global cure rates were significantly higher in the fidaxomicin group (78% vs. 67%, respectively).
In a subgroup analysis, fidaxomicin was associated with lower recurrence rates than was vancomycin, regardless of the patient's white blood cell count, fever, or albumin level.
Also, the recurrence rate was significantly lower with fidaxomicin in patients with non–BI/NAP1/027 C. difficile strains (8% vs. 25%).
Dr. Miller said the safety and adverse events profiles were similar in the two groups, but he did not present specifics on adverse events. Nor were adverse events specified in the trial report on the Optimer Web site.
Dr. Miller is head of the division of infectious diseases at McGill University, Montreal. He did not disclose any relevant conflict of interest.
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