Herbal Remedy Substantially Weakens HIV-fighting
Drug
By Deborah Mitchell
NEW YORK, Feb 11 (Reuters Health) -- One of the most
commonly used herbal remedies, St. John's wort, substantially
reduces blood levels of the HIV-fighting drug indinavir, and may
cause treatment failure in some HIV-infected patients, US
researchers report.
Although St. John's wort (Hypericum perforatum), is marketed as a
treatment for mild depression, little is known about its potential
drug interactions.
Past studies had suggested that St. John's wort and protease
inhibitors -- a particularly effective class of HIV-fighting drugs --
share the same metabolic pathway in the body, according to a
report in the February 12th issue of The Lancet.
To further investigate, researchers at the National Institutes of
Health in Bethesda, Maryland, gave St. John's wort and indinavir
alone and together to 8 healthy, HIV-free volunteers.
The investigators found that St. John's wort substantially reduced
blood levels of the protease inhibitor. After taking St. John's wort,
the level of indinavir dropped by an average of nearly 60% compared
with the level seen without the herbal remedy.
Almost all important HIV drug combinations contain at least one
medication that is metabolized through the same pathway used by
the herbal remedy, noted senior investigator Dr. Judith Falloon of
the National Institute of Allergy and Infectious Diseases in
Bethesda.
Therefore, St. John's wort should be avoided by patients taking
these drugs, "at least until it's figured out how to correct for any
potential interactions." Falloon told Reuters Health.
After completing the study, the researchers immediately checked
to see if they had any patients in their clinic who were taking the
herbal remedy.
"We did have patients who were taking St. John's wort who were on
indinavir," Falloon said. "We promptly called them and told them to
stop."
It is possible that some patients who have failed indinavir therapy
may have done so because they were taking St. John's wort,
according to Falloon.
Many AIDS drug trials have permitted patients to also take
supplements, which fall under the category of nutrition, she added.
"So these substances would not necessarily have been controlled
by clinical trial design."
"I'm certain there are plenty of other... herbal remedies out there
that people use that affect their drug concentrations," she
continued. "It's not uncommon for people to take four or five
supplements." And it's not just a question of drug interactions,
there may well be other unrecognized toxicities, she said.