Dear Health Care Professional:
The Food and Drug Administration would like to
inform you about results from a study conducted by The National
Institutes of Health (NIH) that showed a significant drug interaction
between St. John's Wort (Hypericum perforatum), an herbal product
sold as a dietary supplement, and indinavir, a protease inhibitor
used to treat HIV infection. In this study, concomitant administration
of St. John's Wort and indinavir substantially decreased indinavir
plasma concentrations, potentially due to induction of the
cytochrome P450 metabolic pathway. For additional information
on this study please refer to the
February 12, 2000 Lancet publication (Piscitelli, et al).
RECOMMENDATIONS:
Indinavir and other antiretroviral agents
At this time, pharmacokinetic data are available
only for concomitant administration of indinavir with St. John's
Wort. However, based on these results, it is expected that
St. John's Wort may significantly decrease blood concentrations
of all of the currently marketed HIV protease inhibitors (PIs)
and possibly other drugs (to varying degrees) that are similarly
metabolized, including the nonnucleoside reverse transcriptase
inhibitors (NNRTIs). Consequently, concomitant use of St John's
Wort with PIs or NNRTIs is not recommended because this may
result in suboptimal antiretroviral drug concentrations, leading
to loss of virologic response and development of resistance
or class cross-resistance.
Because herbal products are widely used in the
United States and are available in various forms such as combination
products and teas, it is important that health care professionals
ask patients about concomitant use of products that could contain
St. John's Wort (Hypericum perforatum).
In addition, FDA is working closely with drug
manufacturers to ensure that product labeling of antiretrovirals
is revised to highlight the potential for drug interactions
with St. John's Wort.
Other drugs
Based on this study and reports in the medical
literature, St. John's Wort appears to be an inducer of an
important metabolic pathway, cytochrome P450. As many prescription
drugs used to treat conditions such as heart disease, depression,
seizures, certain cancers or to prevent conditions such as
transplant rejection or pregnancy (oral contraceptives) are
metabolized via this pathway, health care providers should
alert patients about these potential drug interactions to prevent
loss of therapeutic effect of any drug metabolized via the
cytochrome P450 pathway.
All health care professionals are encouraged to
report any serious adverse event associated with the concomitant
use of prescription drugs and St. John's Wort products to the
FDA's MedWatch program at 1-800-FDA-1088 (fax 1-800-FDA-0178). |
