ANNAPOLIS, MD. – Women with bacterial vaginosis could soon have an effective oral, single-dose treatment option, if results of a phase III study result in approval by the Food and Drug Administration.

In a modified intention-to-treat study of 189 women with bacterial vaginosis (BV) randomly assigned 2:1 to treatment or placebo, a single, granulated oral dose of secnidazole 2g was found to be statistically superior to placebo on all clinical endpoints.

Secnidazole (SYM-1219) has a longer half-life, compared with metronidazole, the current treatment standard, according to Jane R. Schwebke, MD, the study investigator and a professor of medicine in the infectious disease department of the University of Alabama, Birmingham. Dr. Schwebke credits the study drug’s high bioavailablility and rapid absorption for its efficacy.

“You get a very high peak with SYM-1219 initially, and I think that might be the reason for the single-dose therapy’s efficacy. It’s due to the pharmacokinetics of the drug itself,” she reported at the annual scientific meeting of the Infectious Diseases Society for Obstetrics and Gynecology.

If the drug is approved, it would likely mean better adherence when compared with current standards of treatment, according to Sharon Hillier, PhD, director of reproductive infectious disease research at the Magee-Women’s Hospital of the University of Pittsburgh.

“It will absolutely improve compliance,” Dr. Hillier said in an interview. “Obviously, it’s much easier than taking [metronidazole] twice a day for 7 days.”

Treatment with metronidazole also requires a week of abstinence from alcohol, compared with what Dr. Hillier anticipates would be 2 or 3 days of alcohol abstinence with secnidazole.

The initial study enrollment was 189 women who were randomized 2:1 to secnidazole or placebo and treated at 21 sites nationally. After assessment for common sexually transmitted diseases, Nugent scores of 4 or greater, and all Amsel criteria (including a vaginal pH of 4.7 or greater, clue cells at or greater than 20%, and a positive KOH whiff test), 164 women remained in the modified intention-to-treat (ITT) analysis. A quarter of all women across the modified ITT group were recurrent BV sufferers, having had at least four episodes of BV in the previous year, and 87% had Nugent scores of 7 or greater.

“These were true BV cases; none were in the intermediate or mild zone,” Dr. Schwebke said.

Responders were women who, between days 21 and 30, had “normal” discharge, less than 20% clue cells, and a negative KOH whiff test. In the study arm, 53.3% of women had “normal” discharge and less than 20% clue cells at their 21-30 day visit, compared with 19.3% in the placebo group (P less than .001). The secondary endpoint – Nugent scores of 3 or less at days 7-14 – was achieved by 43.9% in the study group, compared with 5.3% of controls (P less than .001).

Just over a third of women in the study arm experienced one or more adverse events, compared with 21.9% of controls. Yeast infections were the most common adverse event. Less than 5% of the study group experienced nausea, headache, or diarrhea, compared with up to 3% of controls.

“What’s exciting about this new product is that it will be a single dose oral [that women] can take with a meal and with none of the adverse effects, and it relieves symptoms as well as other treatments,” Dr. Hillier said.

How treatment efficacy should be defined was a matter of debate during the presentation’s question and answer period. The FDA did not issue BV treatment guidance until 1998, despite prior approval of BV treatments clindamycin and metronidazole. The rigorous definition of clinical cure rate put forward in the FDA guidance document caused the cure rates that had been generally accepted by physicians to drop from as high as 80% to around 40%, according to Dr. Hilliard.

“I personally would like to see some head-to-head comparisons of the various treatments we have to know whether some are better than others,” Dr. Hillier said in the interview.

The ideal BV treatment should also provoke a microbiological cure, according to Dr. Schwebke. “What I would do is combine a drug like this with a biofilm inhibitor. Right now, this is great, because it’s single dose oral, and it’s as good as anything out there, but, I don’t think we’re taking the next step necessarily with efficacy.”

The study was supported by Symbiomix. Dr. Schwebke is a consultant for Symbiomix and receives funding from Alfa Wassermann and Starpharma, among others. Dr. Hillier is coprincipal investigator of the Microbicide Trials Network, sponsored by the National Institutes of Health.

wmcknight@frontlinemedcom.com

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Single dose bacterial vaginosis treatment performs well in phase III trial