FDA Approves Secnidazole (Solosec) for Bacterial Vaginosis


September 18, 2017

The US Food and Drug Administration (FDA) last week approved an antibiotic called secnidazole (Solosec, Symbiomix Therapeutics) for women with bacterial vaginosis.

Secnidazole is the first single-dose oral treatment for bacterial vaginosis, the most common vaginal infection in women aged 15 to 44 years, according to the Centers for Disease Control and Prevention.

A dose of secnidazole comes in the form of a 2-g packet of granules. Patients sprinkle the granules on applesauce, yogurt, or pudding and eat the mixture within 30 minutes without chewing or crunching the granules.

Most current antibiotics for bacterial vaginosis must be taken for 5 to 7 days, and often more than once a day. As a single-dose treatment, secnidazole promises to improve adherence and the likelihood of a cure, Symbiomix Therapeutics stated in a news release.

The FDA determined that secnidazole was safe and effective on the basis of two randomized, placebo-controlled clinical trials involving 333 nonpregnant women up to age 54 years. Both trials had three endpoints:

  • A combination of a normal vaginal discharge, a negative test result for amine odor after adding a 10% potassium hydroxide solution to a vaginal-discharge sample, and less than 20% of epithelial cells of the vagina being covered with bacteria (so-called Clue cells).  Someone with all three outcomes was defined as a clinical responder.

  • A "Nugent" score of 3 or lower for the presence of various bacterial cell morphotypes — specifically, large gram-positive rods, small gram-variable or gram-negative rods, and curved gram-variable rods. Such a score indicates a cure.

  • A clinical responder who had a Nugent score of 3 or lower. This score qualified the patient as a therapeutic responder.

One trial assessed these endpoints 21 to 30 days after treatment. The other trial assessed them 7 to 10 days afterward. In both trials, a far higher percentage of patients who took the single dose of secnidazole qualified as both clinical and therapeutic responders and experienced a Nugent-score cure compared with patients who received the placebo.

Vulvovaginal candidiasis, headache, nausea, dysgeusia, vomiting, and diarrhea were among the most common adverse events observed in the two studies. The drug's label warns that vulvovaginal candidiasis associated with the use of secnidazole may require treatment with an antifungal drug.

The agency also warns about the potential risk for carcinogenicity because mice and rats treated chronically with drugs structurally related to secnidazole have developed tumors. "It is unclear if the positive tumor findings in lifetime rodent studies indicate a risk to patients taking a single dose of Solosec to treat bacterial vaginosis," the label states. "Avoid chronic use."

The drug is not recommended for women who are breast-feeding. If they take it, however, they should discontinue breast-feeding for 96 hours afterward.

The label for secnidazole is available on the FDA website.

Follow Robert Lowes on Twitter @LowesRobert


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