Drug Interaction Study of Tegretol (Carbamazepine) and St. John's Wort in Normal Volunteers
Status:
Completed
Trial end date:
2001-04-01
Target enrollment:
Participant gender:
Summary
St. John's Wort is a popular dietary supplement that many patients-including those with
epilepsy or seizures-take in addition to their regular medicines to elevate mood or relieve
stress. Preliminary research indicates that this supplement can speed the metabolism of the
anti-seizure drug Tegretol, causing reduced blood levels of the drug. Patients who take
Tegretol to control their seizures may have more frequent seizures if the blood level of the
drug drops too low. A recent study shows that this effect is not seen when Tegretol is taken
for at least 3 weeks. The present study will examine whether there is a medically important
drug interaction between St. John's wort and Tegretol when Tegretol is taken for 1 day.
Normal healthy volunteers between 21 and 65 years old who are not taking medicines that can
affect the metabolism of drugs in the liver and have not used St. John's wort for at least 30
days may be eligible for this 25-day study.
Participants will take a 400-mg dose of Tegretol after fasting overnight. Blood samples will
be drawn the next day during a 12-hour clinic stay at the following intervals: just before
the Tegretol dose and at 1, 2, 4, 6, 8, 10, 24, 34, 48 and 72 hours after the dose. A
catheter will be placed in the vein to prevent the need for multiple needle sticks until
after the 10-hour sample. After completing the blood sampling, participants will take 300 mg
of St. John's wort 3 times a day with meals for 2 weeks. After 2 weeks, another fasting dose
of Tegretol will be given and the 72-hour blood study will be repeated.
This study may provide information important for the care of patients with epilepsy who take
both Tegretol and St. John's Wort.
Phase:
Phase 4
Details
Lead Sponsor:
National Institutes of Health Clinical Center (CC)