Expired Study
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Kansas City, Kansas 66160


This study will assess the effects of ginseng and ginkgo on 1) cognitive function, 2) enzymes that process drugs, and 3) enzymes that may help prevent cancer.

Study summary:

Over 60 million Americans use herbal medicines; of these, one-fourth also take prescription drugs. Physicians are often unaware of herbal use and of possible drug/herb interactions in their patients. Ginseng and ginkgo, enhancers of physical and mental performance, are two of the most widely taken herbals. We propose a double-blind, randomized, prospective study of effects of ginseng and ginkgo on 1) disposition of probe drugs, 2) cognitive function, and 3) glutathione-S-transferase (GST) and quinone reductase (NQ01), enzymes implicated in chemoprevention of cancer. Probe drugs will be administered to study effects of herbs on their disposition, not for therapeutic effect. Ideal probes must be safe, well tolerated, have minimal pharmacological effect, and share known metabolic pathways with other clinically used drugs. Medically stable drug-free non-smokers will be enrolled. During a 4-week single-blind run-in, subjects will be given a 4-drug probe cocktail: caffeine to study cytochrome P4501A2 (CYP1A2), dextromethorphan for CYP2D6, buspirone (and endogenous cortisol) for CHP3A and fexofenadine for P-glycoprotein. Losartan will be given separately for CYP2C9. These enzymes metabolize over 95% of clinically used drugs. Enzyme activities will be determined by assaying appropriate blood and urine specimens for probe drugs and metabolites. Cognitive function will be tested and blood lymphocytes collected for measuring GST and NQ01 activities. Sixty subjects will then be randomly assigned to one of 4 double-blind treatment groups of 15 each: 1) ginseng extract (Ginsana), 2) ginkgo extract (Egb761), 3) both herbs, or 4) matching placebos. Tolerability of herbs will be determined. After 6 to 8 weeks of twice daily treatment with study agents, all effect parameters will be reevaluated: probe drug pharmacokinetics, cognitive function, and GST and NQ01 in blood lymphocytes. Interactions of chronic ginseng and ginkgo with drug-metabolizing pathways and with cognitive function will thus be determined.


Inclusion Criteria: - Acceptable weight and laboratory test values Exclusion Critera: - Abuse of drugs, tobacco, or alcohol - Chronic physical complaints or serious allergies - Illnesses requiring chronic drug ingestion - Use of herbs, high-dose vitamins, or non-traditional diets

Study is Available At:

Original ID:

R01 AT000842-01



Secondary ID:

Study Acronym:

Brief Title:

Effects of Ginseng and Ginkgo on Drug Disposition in Man

Official Title:

Effects of Ginseng and Ginkgo on Drug Disposition in Man

Overall Status:


Study Phase:

Phase 2



Minimum Age:

20 Years

Maximum Age:


Quick Facts

Healthy Volunteers
Oversight Has DMC
Study Is FDA Regulated
Study Is Section 801
Has Expanded Access

Study Source:

National Center for Complementary and Alternative Medicine (NCCAM)

Oversight Authority:

United States: Federal Government

Reasons Why Stopped:

Study Type:


Study Design:

Allocation: Randomized, Masking: Double-Blind, P

Number of Arms:


Number of Groups:


Total Enrollment:


Enrollment Type:

Study Dates

Start Date:March 2002
Completion Date:March 2005
Verification Date:July 2006
Last Changed Date:July 24, 2006
First Received Date:January 18, 2002

Study Outcomes

There are no available Study Outcomes

Study Interventions

Intervention Type:Drug
Intervention Type:Drug

Study Arms

There are no available Study Arms

Study Agencies

Agency Class:NIH
Agency Type:Lead Sponsor
Agency Name:National Center for Complementary and Alternative Medicine (NCCAM)

Sample and Retention Information

There are no available Sample and Retention Information

Study References

There are no available Study References

Data Source: ClinicalTrials.gov

Date Processed: January 21, 2020

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