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Effect of Amlodipine on Anti-platelet Drug Effect in Patients With Coronary Artery Disease

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01203696
Recruitment Status : Completed
First Posted : September 16, 2010
Last Update Posted : June 6, 2012
Information provided by (Responsible Party):
Ruttonjee Hospital

Brief Summary:

Clopidogrel can reduce risk of cardiovascular disease by inhibiting platelet aggregation. It is metabolized to an active drug by a liver enzyme. Its efficacy may be measured by blood sampling for platelet activity, analyzed by VerifyNow device. Calcium Channel blocker (CCB) is also commonly used for blood pressure and anginal control in these patients. Dihydropyridine group of calcium channel blocker (e.g. amlodipine) inhibits this enzyme. There are observational studies reporting dihydropyridine CCB reducing clopidogrel effect, but the clinical implication is unclear.

This study test the hypothesis that there is no significant effect of dihydropyridines CCB on clopidogrel response compared with control. After giving consent, patients with suboptimal blood pressure or anginal control will be randomized to receive either dihydropyridine CCB or non-CCB as placebo. These patient will be follow-up in 1 month.

Condition or disease Intervention/treatment Phase
Ischemic Heart Disease Drug: Amlodipine Phase 4

Detailed Description:

Clopidogrel is a pro-drug, which requires hepatic transformation by the cytochrome P450 isoform 3A4 to generate the active metabolite. It inhibits adenosine-5-diphosphate (ADP)-induced platelet aggregation by irreversibly blocking the platelet P2Y12 receptor. However, response to clopidogrel shows wide individual variability, and patients with high on-treatment residual ADP-induced platelet reactivity are at an increased risk of adverse cardiovascular events. Previous study suggest co-administration of CCBs is associated with decreased platelet inhibition by clopidogrel, but these observational studies are confounded by patient's characteristics baseline difference such as proportion of hypertension and diabetes.

The objective of this randomized controlled study is to compare amlodipine with placebo on anti-platelet effect of clopidogrel.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 97 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Effect of Amlodipine on Platelet Inhibition by Clopidogrel in Patients With Ischemic Heart Disease- a Prospective Randomized Controlled Trial
Study Start Date : July 2010
Actual Primary Completion Date : April 2011
Actual Study Completion Date : April 2011

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Active Comparator: non-amlodipine
For patient with suboptimal angina control: anti-anginal agent excluding calcium channel blocker
Drug: Amlodipine
For patient with suboptimal angina control: oral 2.5-10mg daily
Other Name: Norvasc

Active Comparator: non - amlodipine
For patient with suboptimal BP control: anti-hypertensive agent excluding calcium channel blocker
Drug: Amlodipine
For patient with suboptimal BP control: 2.5-10mg daily po
Other Name: Norvasc

Primary Outcome Measures :
  1. Platelet reactivity unit [ Time Frame: baseline and 4 th week ]
    Platelet reactivity unit as measured by VerifyNow system

Secondary Outcome Measures :
  1. Percentage inhibition of platelet activity [ Time Frame: baseline and 4th week ]
    Percentage inhibition of platelet activity measured by VerifyNow system

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • ischemic heart disease patient, and
  • given loading or maintenance dose of clopidogrel and in need of it for 1 or more month
  • and in need of additional drug for optimal BP control (aim blood pressure <130/90) or angina control.

Exclusion Criteria:

  • existing use of amlodipine
  • thrombocytopenia
  • end stage renal failure
  • allergy to clopidogrel/ amlodipine
  • pregnancy/ lactation
  • strong inhibitor or inducer of cytochrome P450 3A4 enzyme within 7 days before start of the study.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01203696

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Ruttonjee Hospital
Hong Kong SAR, China
Sponsors and Collaborators
Ruttonjee Hospital
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Principal Investigator: Andrew YW Li, MB Ruttonjee Hospital
Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: Ruttonjee Hospital Identifier: NCT01203696    
Other Study ID Numbers: Aml-Clo-protocol-v1
First Posted: September 16, 2010    Key Record Dates
Last Update Posted: June 6, 2012
Last Verified: June 2012
Keywords provided by Ruttonjee Hospital:
Platelet reactivity
Additional relevant MeSH terms:
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Heart Diseases
Myocardial Ischemia
Coronary Artery Disease
Pathologic Processes
Cardiovascular Diseases
Vascular Diseases
Coronary Disease
Arterial Occlusive Diseases
Antihypertensive Agents
Calcium Channel Blockers
Membrane Transport Modulators
Molecular Mechanisms of Pharmacological Action
Calcium-Regulating Hormones and Agents
Physiological Effects of Drugs
Vasodilator Agents