Conditions: Metabolism of Clopidogrel
Keywords: Clopidogrel Pharmacogenetics Platelets Healthy Subjects
Allocation: NON_RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 18
Healthy volunteers: yes

Brief summary:
Clopidogrel (also known as Plavix) is used commonly in patients to prevent heart attacks and conditions caused by blood clots. Although clopidogrel works in many individuals, some people do not respond as well to this drug. The variation in treatment response may be linked to genetics. This study will examine the effects of clopidogrel in a population in which sequencing for certain genes has been performed in order to determine the role that genes play in the response to various clopidogrel maintenance doses.

Detailed description:
Clopidogrel is a prodrug with high inter-individual response variability. Clopidogrel is converted to an active drug in part through an enzyme encoded by the gene named CYP2C19. Individuals with genetically-impaired CYP2C19 metabolism have lower capacity to convert the prodrug to its active form. Consequently, these individuals have lower blood levels of the activated form of clopidogrel, diminished antiplatelet responses, and higher rates of cardiovascular events and stent thrombosis. Increasing doses of clopidogrel in such patients represents a possible approach to managing the gene-drug interaction.

The purpose of this study is to evaluate whether increasing the dose of clopidogrel increases antiplatelet responses and active metabolite exposure in individuals with genetically reduced CYP2C19 metabolism relative to those with normal CYP2C19 metabolism.

The primary objective is to assess changes in clopidogrel response and exposure at three clopidogrel dose levels and with coadministration of omeprazole.

Arms:
arm 1: Healthy subjects who have been genotyped for CYP2C19\*2 and received clopidogrel as part of a prior study (PAPI) will be recruited. We will select 6 poor metabolizers (PM) to clopidogrel 75 mg from participants who previously received 75 mg clopidogrel as part of another NIH sponsored clinical trial entitled, "Pharmacogenetics of Anti-platelet Intervention" (PAPI) Study (NCT 00799396). Over a 6 week period participants will be given: 75 mg of clopidogrel for 8 days, at least 1 week washout, 150 mg of clopidogrel for eight days, at least 1 week washout, 300 mg of clopidogrel for eight days. arm 2: Healthy subjects who have been genotyped for CYP2C19\*2 and received clopidogrel as part of a prior study (PAPI) will be recruited. We will select 6 intermediate metabolizers (IM) to clopidogrel 75 mg from participants who previously received 75 mg clopidogrel as part of another NIH sponsored clinical trial entitled, "Pharmacogenetics of Anti-platelet Intervention" (PAPI) Study (NCT 00799396). Over a 6 week period participants will be given: 75 mg of clopidogrel for 8 days, at least 1 week washout, 150 mg of clopidogrel for eight days, at least 1 week washout, 300 mg of clopidogrel for eight days. arm 3: Healthy subjects who have been genotyped for CYP2C19\*2 and received clopidogrel as part of a prior study (PAPI) will be recruited. We will select 6 extensive metabolizers (EM) to clopidogrel 75 mg from participants who previously received 75 mg clopidogrel as part of another NIH sponsored clinical trial entitled, "Pharmacogenetics of Anti-platelet Intervention" (PAPI) Study (NCT 00799396). Over a 6 week period participants will be given: 75 mg of clopidogrel for 8 days, at least 1 week washout, 150 mg of clopidogrel for eight days, at least 1 week washout, 300 mg of clopidogrel for eight days. arm 4: PM participants who have completed Arm 1 will have the option to participate. After a washout of at least one week, these participants will given 75 mg of clopidogrel together with 20 mg of omeprazole daily for eight days. arm 5: IM participants who have completed Arm 2 will have the option to participate. After a washout of at least one week, these participants will given 75 mg of clopidogrel together with 20 mg of omeprazole daily for eight days. arm 6: EM participants who have completed Arm 3 will have the option to participate. After a washout of at least one week, these participants will given 75 mg of clopidogrel together with 20 mg of omeprazole daily for eight days.

Interventions: intervention 1: Clopidogrel intervention 2: Omeprazole/Clopidogrel
Intervention descriptions: intervention 1: Over a 6 week period participants will be given: 75 mg of clopidogrel for 8 days, at least 1 week washout, 150 mg of clopidogrel for eight days, at least 1 week washout, 300 mg of clopidogrel for eight days. intervention 2: After a washout of at least 1 week, participants will have the option to participate in a final intervention in which they will be given 75 mg of clopidogrel together with 20 mg of omeprazole daily for eight days.

Protocol document: