Estrogen is no longer the preferred therapy because recent, large studies have shown that the hormone increases the risk of heart disease, stroke, breast cancer and Alzheimer's disease for some women. Given that news, millions of women have abandoned hormone replacement therapy (HRT) and are seeking other ways to ease symptoms. So-called natural remedies such as soy, herbal products or acupuncture have not proven safe or effective at this point.
The latest Rochester study is the first to compare gabapentin and estrogen head-to-head against a placebo. Although it showed a substantial placebo effect similar to other menopause studies - women taking the sugar pill reported a 54-percent reduction in hot flashes - the women taking gabapentin and estrogen reported even better results, with a 71 percent to 72 percent decline in symptoms.
"Gabapentin does appear to be as effective as estrogen," said lead author Sireesha Y. Reddy, M.D., assistant professor of Obstetrics and Gynecology at the University of Rochester Medical Center. "Until now its efficacy relative to estrogen was unknown."
Approximately 75 percent of postmenopausal women between the ages of 35 and 60 experience hot flashes. Gabapentin (sold under the trade name Neurontin) was approved by the FDA in 1994 to treat epileptic seizures but has been used off-label for years to treat headaches, shingles pain and other ailments. Scientists hypothesize that gabapentin may reduce hot flashes by regulating the flow of calcium in and out of cells, which is one mechanism for controlling body temperature.
An expert panel on menopause convened by the National Institutes of Health last year cautioned against the tendency to use treatments with scant safety data, and concluded that nothing to date was as effective as estrogen therapy although more research was needed.
In the latest study, Reddy and colleagues enrolled 60 women in a randomized, double-blind, placebo-controlled trial for 12 weeks. Initially the researchers received more than 1,500 calls from women who wanted to participate, but after screening the callers to meet the study's protocol, the number was whittled to 60, with 53 women complying with every step.
They were randomly divided into three groups: 20 women received gabapentin at 2,400 mg per day and a daily placebo or fake estrogen pill; 20 received estrogen in the form of Premarin at 0.625 mg per day and a fake gabapentin pill; 20 received sugar pills resembling gabapentin and estrogen. The women recorded the frequency and severity of their hot flashes in diaries.
Results were tabulated using two statistical methods to compare the women's hot flash reports throughout the 12-week period with their baseline symptoms. Doctors did find that women who took gabapentin complained more often of headaches, dizziness or disorientation. Researchers believe that slowly ramping up the medication and taking it with meals can alleviate the side effects.
The NIH funded the study. Pfizer Inc. supplied gabapentin but had no role in the research. A co-author on the paper, Thomas Guttuso Jr., M.D., has a patent for the use of gabapentin in the treatment of hot flashes. Guttuso is a former neurologist at the University of Rochester who is now on the faculty at the University of Buffalo.