CompletedPhase 1

Effect of Ginkgo Biloba on Phenytoin Elimination

United States12 participantsStarted 2001-02

Plain-language summary

This study will examine how the herbal remedy ginkgo biloba may affect the body's elimination of other medicines. Many people take ginkgo biloba to improve memory, mental alertness and overall feeling of well being. Since this product is considered a food supplement and not a drug, it is not subject to the rigorous pre-market testing required for prescription and over-the-counter (OTC) drugs. As a result, information has not been collected on possible interactions between ginkgo biloba and other medications. This study will look at how ginkgo biloba affects the elimination of phenytoin-a medication used to treat patients with seizures. Normal healthy volunteers 21 years of age or older may be eligible for this 40-day study. Candidates will provide a medical history and undergo a physical examination and routine blood tests. Women of childbearing age must use a reliable form of birth control other than oral contraceptives ("the pill"). For at least 2 weeks before the study and throughout its duration, study participants may not have any of the following: 1) medications that can affect platelet function (e.g., aspirin, Motrin, Advil, Nuprin, ibuprofen, etc.); 2) alcoholic beverages; 3) grapefruit and grapefruit juice; and 4) all medications except those given by study personnel. On day 1 of the study, subjects take one 500-mg dose of phenytoin at 8:00 A.M.. On an empty stomach. (Subjects fast the night before taking the phenytoin and are allowed to eat breakfast 2 hours after the dose). Blood samples are drawn just before dosing and again at 0.5, 1, 1.5, 2, 4, 6, 8, 10, 12, 24, 32, 48, 72 and 96 hours after the dose. Blood drawn on this first study day is collected through a catheter (small plastic tube) placed in a vein to avoid multiple needlesticks. After the 12-hour sample is collected, the subject goes home and then returns to the clinic for the remaining blood draws, which are taken by direct needlestick. When the blood sampling is completed, subjects begin ginkgo therapy. The NIH Clinical Center provides participants a supply of 60-mg capsules of ginkgo to take twice a day (at 8 A.M. and 8 P.M..) for 4 weeks. At the end of the 4 weeks, subjects are given a second dose of phenytoin as described above and repeat the blood sampling procedure. Subjects continue taking ginkgo during this second phenytoin study.

Who can participate

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Male or female. Healthy by medical history and physical exam. Age greater than 21 years old. No concurrent medications. Non-smoker (for at least 6 months if prior history of smoking). Laboratory values wihin the following guidelines: AST/SGOT less than or equal to 1.5 times the upper limit of normal; bilirubin less than or equal to the upper limit of normal; serum creatinine less than or equal to the upper limit of normal; hemoglobin greater than or equal to 10 g/dl; albumin NML. 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. Must have the ability to remain free of chronic medications and alcohol for at least 2 weeks prior to and during the study. No use of oral contraceptives (phenytoin, and potentially ginko, may induce the clearance of oral contraceptive lead to potential oral contraceptive failure). Must have the ability and willingness to avoid analgesics with antiplatelet activity for at least 2 weeks prior to and during the study. 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 principal investigator. No positive serum pregnancy test. No presence of p…

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

Trial details

NCT IDNCT00011063

SponsorNational Institutes of Health Clinical Center (CC)

Sponsor typeNIH

Study typeINTERVENTIONAL

View on ClinicalTrials.gov More Healthy trials

Plain-language summary

Who can participate

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.