By David Douglas
NEW YORK (Reuters Health) Apr 13 - A new higher-dose formulation of once-a-day doxycycline worked as well as the standard twice-daily capsules in men and women with uncomplicated urogenital Chlamydia infection in a phase III trial.
The new daily 200-mg tablet could improve adherence, said lead investigator Dr. William Geisler of the University of Alabama at Birmingham and colleagues in a paper online in Clinical Infectious Diseases.
The tablet is being developed by Warner Chilcott, which already markets once-daily doxycycline as Doryx, in 75-, 100-, and 150-mg tablets.
The researchers note an alternative to twice-daily doxycycline: a single dose of azithromycin. But recent studies have been questioning its effectiveness, and Dr. Geisler told Reuters Health by email that given those concerns, "and the risk for Chlamydia treatment failure with nonadherence to a twice daily seven-day doxycycline regimen, it is important to investigate new Chlamydia treatment regimens."
"In the past 15 years," he added, "there has been sparse research re-evaluating Chlamydia therapy or investigating new Chlamydia treatments, especially those that could improve treatment adherence over twice-daily doxycycline regimens."
The recent trial of the new 200-mg delayed-release formulation involved 19- to 45-year-old men and women with urogenital Chlamydia infection or a sexual partner with Chlamydia. They were randomly assigned to receive either the investigational tablet WC2031 once daily or 100 mg of Vibramycin (Pfizer's doxycycline capsule) twice daily for seven days.
After exclusions, mainly because of negative test results for C. trachomatis at enrollment, 323 participants were evaluable for efficacy.
Microbial cure rates were 95.5% for WC2031 and 95.2% for Vibramycin. Adverse events were generally comparable, although the rate of nausea was lower with WC2031 (13% vs 21%), as was the rate of vomiting (8% vs 12%).
"The comparable efficacy and safety of once daily WC2031 for seven days compared to twice daily doxycycline for seven days for uncomplicated Chlamydia treatment suggests WC2031 could be a promising future treatment option for Chlamydia, and the once daily dosing of WC2031 simplifies Chlamydia treatment compared with a twice daily doxycycline regimen," Dr. Geisler said.
Warner Chilcott did not respond to inquiries about the FDA status of WC2031.
Clin Infect Dis 2012.
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