NEW YORK (Reuters Health) - For the topical treatment of bacterial vaginosis (BV), the combination of metronidazole plus nystatin ovules is significantly more effective than metronidazole gel, according to results of a randomized controlled trial conducted in Lima, Peru.

The study findings also suggest that unprotected sex increases the risk of recurrence of BV after initial improvement.

In Latin America, metronidazole 500 milligrams plus nystatin 100,000 units in intravaginal ovules administered nightly for 5 to 7 nights is often prescribed for vaginal discharge. The lack of published studies assessing the efficacy of this unproven approach prompted Dr. Sixto Sanchez and colleagues to compare it to metronidazole 0.75% gel once nightly for 5 nights, which is approved by the U.S. FDA.

Of 151 women with BV randomized to one of the two treatments, 138 (91%) returned at least once for follow-up, the authors note in the December issue of the American Journal of Obstetrics and Gynecology.

Rates of persistent or recurrent BV at 14, 42, and 104 days were 20%, 38%, and 52%, respectively, after gel treatment, compared with 4%, 17%, and 33% after ovule treatment (p = 0.01).

"Significant differences in persistent or recurrent clinical and microbiologic manifestations of BV were evident as early as the first follow-up visit within 21 days, and persisted throughout the follow-up period of 3 months," the team notes.

The authors think that the higher content of metronidazole in the ovules (500 mg) compared with the gel (37.5 mg per dose) may explain the better efficacy of this treatment, although additional studies are needed.

Am J Obstet Gynecol 2004;191:1898-1906.

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