Women who take hop-based supplements to relieve symptoms of menopause needn't fear that they will interact with other drugs, a new study suggests.
Hops are the flowers of hop plants and they give beer its bitter taste. They also contain phytoestrogens and act like female sex hormones. Some women who can't use hormone replacement therapy find that hop supplements alleviate change-of-life complaints such as night sweats and hot flashes.
However, there's been concern about drug interactions. "There are reports from other lab studies that compounds from hops may inhibit or deactivate certain drug-metabolizing enzymes," said study researcher Richard van Breemen, director of Oregon State University's Linus Pauling Institute.
"There is additional concern because we know the compounds in hops have a long half-life in humans, possibly more than 20 hours after taking them," he said in a university news release. This means these supplements remain in the bloodstream when other drugs are taken.
To see if hops interacted with other drugs, researchers worked with 16 female participants at menopausal age. They were given a cocktail of four drugs, including caffeine, alprazolam (Xanax), dextromethorphan (an over-the-counter cough medicine) and tolbutamide, used to treat type 2 diabetes.
"We did each drug trial twice. Once to see how these women metabolized the drugs normally," van Breemen said. "Then we repeated the trial with hops after the participants took a hops extract twice daily for two weeks. Thankfully, no enzyme inhibition was detected."
Using U.S. Food and Drug Administration guidelines, the researchers found the hop supplement "caused no clinically relevant pharmacokinetic interactions," said study co-author Luying Chen, a Ph.D. student in van Breemen's lab.
"So we can say that hop dietary supplements are not expected to produce any harmful drug interactions, at least with respect to the enzymes probed during this investigation," Chen said in the release. "More research is needed, but these findings are good news for women who take hops for relief of menopause symptoms."
The report was recently published in the Journal of Agricultural and Food Chemistry.
For more on menopause, see the U.S. National Institute on Aging.