Treatment with desvenlafaxine succinate, an experimental nonhormonal therapy, continues to reduce the frequency and severity of moderate to severe hot flashes out to 26 weeks.
The drug, a selective serotonin norepinephrine reuptake inhibitor (SNRI), has already been shown to be effective in relieving this bothersome menopausal symptom in a 12-week trial, which was reported last year.
The current findings, from an extension of that trial, show that desvenlafaxine continues to be effective for more than 6 months, said Dr. Risa Kagan, professor of obstetrics, gynecology, and reproductive sciences at the University of California, San Francisco, and a consultant for Wyeth, which developed the drug.
“This is good news for the many women who are bothered [by hot flashes] and who are looking for alternatives to estrogen or hormone replacement therapy,” she said in an interview.
In the continuation of the multicenter, randomized, double-blind, placebo-controlled trial, 541 women who had at least 50 moderate to severe hot flashes per week and who received 150 mg/day of desvenlafaxine maintained the significant reduction in the number of hot flashes they had achieved by week 12 of the trial (from 10 per day to 2 per day) for the duration of the 26-week study, she said at the annual meeting of the North American Menopause Society.
The improvement in hot flash frequency and severity was dose dependent. The 118 women who were randomized to desvenlafaxine 100 mg/day had a less robust decrease in hot flash frequency, and went from an average of 10 to 4 hot flashes per day by week 26. The 138 women who were randomized to placebo also saw a reduction in their hot flashes from baseline, from an average of 10 to 6 per day.
The women recorded their hot flash episodes in diaries and were assessed weekly for the first 12 months, and then every 3 weeks thereafter.
The reductions from baseline in the frequency of moderate to severe hot flashes “were significantly greater, compared with placebo, at all time points with desvenlafaxine 150 mg and at most time points with desvenlafaxine 100 mg throughout the 26 weeks of the study,” Dr. Kagan said.
The most common adverse event was nausea, which was mild to moderate and improved with time. “Nausea is not unique to this agent, and is something that is associated with many of this category of drugs. However, it was responsible for about 12.7% of the desvenlafaxine subjects' withdrawing from the study,” she said.
Fluctuations and the eventual decline in estrogen levels during menopause may cause alterations in brain serotonin and norepinephrine transmitter levels, which may in turn produce instability in thermoregulatory function and, as a result, hot flashes, Dr. Kagan explained. “The hope is that drugs like desvenlafaxine, which act on these transmitters, may provide nonhormonal relief of menopausal vasomotor symptoms.”