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The Impact of Grapefruit Juice on the Response to Clopidogrel

The Impact of Grapefruit Juice on the Response to a Loading Dose and Maintenance Dose of Clopidogrel in Healthy Volunteers

Status
Completed
Phases
Phase 4
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT00817999
Enrollment
32
Registered
2009-01-07
Start date
2008-11-30
Completion date
2011-07-31
Last updated
2012-10-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy

Keywords

Platelet Aggregation Inhibition

Brief summary

This study will measure the percentage of platelet aggregation inhibition with a loading dose of clopidogrel (300 mg) using the VerifyNow Assay System in healthy volunteers who have drank 11 oz of grapefruit juice. It will also measure the percentage of platelet aggregation inhibition with a maintenance dose of clopidogrel (75 mg/day) using the VerifyNow Assay System in healthy volunteers who have drank 11 oz grapefruit juice daily.

Detailed description

This study will examine the effect of GFJ on the loading dose (300 mg) of clopidogrel and will evaluate the effect of GFJ on the maintenance dose (75 mg/day) of clopidogrel. Subjects will be randomized to either initially receive GFJ prior to their loading dose of clopidogrel or receive GFJ prior to their second loading dose. The subjects who have been randomized to receive GFJ initially will drink two small cans (11 oz total) of regular strength GFJ in the morning, followed two hours later by a loading dose (300 mg) of clopidogrel and will then return to the clinic 6 hours after their loading dose to have their platelet inhibition measured. Subjects will have \ 5 milliliters (1 teaspoonful) of whole blood drawn from an antecubital vein in their forearm via a 21 gauge needle attached to a blue-top plastic vacuette sodium citrate blood collection (Greiner, Monroe, NC) tube to test inhibition of platelet aggregation. After their first loading dose, a 2 week washout period will follow to allow for their platelet aggregation to return to normal. Following the washout period, the subjects will take their second loading dose of clopidogrel and again return to the clinic for platelet inhibition measurement. The same timing will be followed for the loading dose taken without prior GFJ. During the maintenance dose phase of this study, subjects will take 75 mg/day clopidogrel for 7 days with or without GFJ. Subjects will be randomized to either GFJ during the first period or GFJ during the second period. A minimum 2 week washout period will occur between the two 7 day courses of clopidogrel. Platelet inhibition measurement will occur at the end of each 7 day period as described above.

Interventions

DIETARY_SUPPLEMENTGrapefruit juice

Participants received grapefruit juice during 1 of the 2 periods.

DRUGClopidogrel 75 mg/day

Sponsors

Creighton University
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
SCREENING
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
19 Years to 40 Years
Healthy volunteers
Yes

Inclusion criteria

* Ages 19-40 * Health status confirmed by medical history and physical examination and laboratory analysis

Exclusion criteria

* Pregnancy * Taking routine prescription or over-the-counter prescriptions * Taken over-the-counter analgesic/anti-inflammatory medication within two weeks of study participation * Recently had grapefruit juice or regularly drinks grapefruit juice

Design outcomes

Primary

MeasureTime frameDescription
% Platelet Inhibition6 hours% platelet inhibition measured by Verify Now

Countries

United States

Participant flow

Participants by arm

ArmCount
Loading Dose15
Maintenance Dose17
Total32

Baseline characteristics

CharacteristicMaintenance DoseLoading DoseTotal
Age, Categorical
<=18 years
0 Participants0 Participants0 Participants
Age, Categorical
>=65 years
0 Participants0 Participants0 Participants
Age, Categorical
Between 18 and 65 years
17 Participants15 Participants32 Participants
Age Continuous25.47 years
STANDARD_DEVIATION 5.66
24.4 years
STANDARD_DEVIATION 5.9
25.47 years
STANDARD_DEVIATION 5.66
Region of Enrollment
United States
17 participants15 participants32 participants
Sex: Female, Male
Female
13 Participants10 Participants23 Participants
Sex: Female, Male
Male
4 Participants5 Participants9 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
— / —— / —
other
Total, other adverse events
0 / 150 / 17
serious
Total, serious adverse events
0 / 150 / 17

Outcome results

Primary

% Platelet Inhibition

% platelet inhibition measured by Verify Now

Time frame: 6 hours

ArmMeasureValue (MEAN)Dispersion
Loading Dose With Grapefruit Juice% Platelet Inhibition23.4 percentage of platelet inhibitionStandard Deviation 14.2
Maintenance Dose With Grapefruit Juice% Platelet Inhibition24.6 percentage of platelet inhibitionStandard Deviation 24.2
Loading Dose Without Grapefruit Juice% Platelet Inhibition41.2 percentage of platelet inhibitionStandard Deviation 19.1
Maintenance Dose Without Grapefruit Juice% Platelet Inhibition59 percentage of platelet inhibitionStandard Deviation 22.5

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026