No interaction between St. John's wort and epilepsy drug
In a study designed to investigate potential interactions between
St. John's wort (Hypericum perforatum) and the drug carbamazepine,
researchers detected no significant differences in blood concentrations
or clearance of the drug before or after administration of St.
John's wort. The study involved eight healthy volunteers who took
St. John's wort in combination with carbamazepine, an anticonvulsant
drug marketed under the trade name Tegretol®. An earlier study
conducted by the same research team reported that St. John's wort
lowered blood concentrations of indinavir, a protease inhibitor
used to treat HIV infection, in healthy volunteers. Like many
other drugs, carbamazepine and indinavir are metabolized via the
same cytochrome P-450 liver enzyme, CYP3A4. The new study refutes
the widespread speculation that St. John's wort lowers blood concentrations
of all drugs metabolized via this enzyme system. According to
the study authors, up to 7% of people with epilepsy use St. John's
wort to improve mood and reduce fatigue. Burstein AH, Horton
RL, Dunn T, et al. Lack of effect of St. John's wort on carbamazepine
pharmacokinetics in healthy volunteers. Clinical Pharmacology
and Therapeutics 2000; 68: 6.
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