CompletedPhase 4

Effects of Kava on the Body's Elimination of Caffeine and Dextromethorphan

United States20 participantsStarted 2001-01

Plain-language summary

This study will examine how kava-a widely used herbal remedy-may affect the body's elimination of other medicines. Many people take kava to reduce anxiety or cause sedation. 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 kava and other medications. This study will look at how kava affects the elimination of caffeine-a compound commonly found in chocolate, coffee, tea and soft drinks-and dextromethorphan-an OTC cough suppressant. Normal healthy volunteers 21 years of age or older may be eligible for this 30-day study. Candidates will provide a medical history and undergo a physical examination and routine blood tests. Women of childbearing age will have a urine pregnancy test. Study participants will not drink alcoholic beverages or take any medications (except those given in the study) for 2 weeks prior to the study and throughout its duration. In addition, they will abstain from caffeine, grapefruit and grapefruit juice and charbroiled foods for at least 72 hours before and throughout each study day that urine is collected. On day 1 of the study, study subjects will take one dose each of caffeine and dextromethorphan at 4:00 P.M.. They will empty their bladder before the dosing and then collect all their urine after the dosing for the rest of the day and including the next mornings first urine. They will bring the urine samples to the Clinical Center when the collection is complete. This procedure will be repeated 1 week later (study day 8). After the second urine collection is completed, subjects will take 200 milligrams of kava 3 times a day for 21 days. On study day 29 (after 21 days of kava), subjects will repeat the dextromethorphan and caffeine dosing and urine collection described above, while continuing to take kava. Subjects will have an electroencephalograph (EEG) done before starting kava and again at the end of kava (study day 30). For this procedure, several electrodes (metal cups attached to wires) are secured to the scalp with a glue-like substance. A conductive gel fills the space between the electrode and the scalp to ensure good contact. The electrodes will remain in place for about 2 hours and then removed. The subject lies quietly on a bed during the EEG recording. Participation in the study will end with another physical examination and blood tests following the second EEG and urine collection.

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 within the following guidelines: AST/SGOT less than or equal 1.5 X ULN Bilirubin less than or equal 1.5 X ULN Serum creatinine less than or equal ULN Hemoglobin less than 10 g/dl Females of child bearing potential must be using a reliable form of birth control other than hormonal contraceptives Ability to abstain from caffeine containing foods/beverages, ethanol, grapefruit or grapefruit juice and charbroiled foods for 72 hours prior to, and the day of, phenotyping procedures. Normal EEG during baseline testing. No patients using concomitant therapy with other inhibitors or inducers of cytochrome P-450 mediated drug metabolism within 30 days of study. No patients with inability to remain free of chronic medications and alcohol for atleast 2 weeks prior to and during the study. 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. Positive urine pregnancy test. The presence of persistent diarrhea or malabsorption that would interfere with the patient's ability to adequately absorb drug. Drug or alcohol use that may impair safety or adherence.

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 IDNCT00009542

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.