Drug Interaction Study of Tegretol (Carbamazepine) and St. John's Wort in Normal Volunteers

• Status: Completed
• Trial end date: 2001-04-01
• Target enrollment: 0
• Participant gender: All

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
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: National Institutes of Health Clinical Center (CC)
• Treatments: Carbamazepine

Criteria

Male or female.

Healthy by medical history and physical exam.

Age between 21 and 65 years old.

Non-smoker for a minimum of 6 months.

AST/SGOT less than or equal to 2 x upper limit of normal.

Serum creatinine less than or equal to upper limit of normal.

Hemoglobin greater than or equal to 10 g/dl.

Females of childbearing potential must be using a reliable form of birth control other than hormonal contraceptives.

No concomitant therapy with other inhibitors or inducers of cytochrome P-450 mediated drug metabolism within 30 days of study.

No inability to remain free of chronic medications and alcohol for at least 2 weeks prior to and during the study.

No previous use of St. John's Wort. Subjects with prior history of St. John's Wort use must abstain from use for 30 days prior to study participation.

No presence of renal, hepatic, cardiovascular, hematologic, neurologic, psychiatric, or respiratory disease or any other condition that may interfere with the interpretation of the study results or not be in the best interests of the subject in the opinion of the investigator.

No positive urine pregnancy test.

No presence of persistent diarrhea or malabsorption that would interfere with the patients ability to adequately absorb drugs.