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

This study has been completed.
Information provided by (Responsible Party):
Ruttonjee Hospital Identifier:
First received: September 15, 2010
Last updated: June 5, 2012
Last verified: June 2012

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 Intervention Phase
Ischemic Heart Disease Drug: Amlodipine Phase 4

Study Type: Interventional
Study Design: 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

Resource links provided by NLM:

Further study details as provided by Ruttonjee Hospital:

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

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

Enrollment: 97
Study Start Date: July 2010
Study Completion Date: April 2011
Primary Completion Date: April 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
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

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.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
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.
  Contacts and Locations
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Please refer to this study by its identifier: NCT01203696

Ruttonjee Hospital
Hong Kong SAR, China
Sponsors and Collaborators
Ruttonjee Hospital
Principal Investigator: Andrew YW Li, MB Ruttonjee Hospital
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Ruttonjee Hospital Identifier: NCT01203696     History of Changes
Other Study ID Numbers: Aml-Clo-protocol-v1
Study First Received: September 15, 2010
Last Updated: June 5, 2012

Keywords provided by Ruttonjee Hospital:
Platelet reactivity

Additional relevant MeSH terms:
Heart Diseases
Myocardial Ischemia
Coronary Artery Disease
Pathologic Processes
Cardiovascular Diseases
Vascular Diseases
Coronary Disease
Arterial Occlusive Diseases
Calcium Channel Blockers
Platelet Aggregation Inhibitors
Purinergic P2Y Receptor Antagonists
Purinergic P2 Receptor Antagonists
Purinergic Antagonists
Purinergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Physiological Effects of Drugs
Antihypertensive Agents
Membrane Transport Modulators
Vasodilator Agents processed this record on August 18, 2017