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Impact of Citalopharm and Fluvoxamine on Platelet Response to Clopidogrel

This study has been completed.
ClinicalTrials.gov Identifier:
First Posted: July 19, 2011
Last Update Posted: January 29, 2013
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.
Information provided by (Responsible Party):
RONNY ALCALAI, Hadassah Medical Organization

Clopidogrel is a platelets inhibitor that is widely used particularly during and after acute coronary events and coronary interventions. Several studies have shown that some patients are resistant to clopidogrel. The resistance mechanism is not entirely clear, but at least in part it is related to interactions between medications. Clopidogrel is a pro-drug converted in vivo to its active metabolite by CYP2C19 and CYP3A in the liver. Consequently drugs that inhibit the CYP2C19 can affect the production of the active metabolite and cause "clopidogrel resistance". Therefore the FDA has recently published a "safety alert" which recommends avoiding cross treatment with clopidogrel and drugs that are expected to inhibit CYP2C19 (including omeprazole, fluvoxamine, cimetidine, fluconazole and others). Nevertheless there no clear evidence in the literature for clinical relevance of such interactions.

Selective serotonin reuptake inhibitors (SSRIs) are group of antidepressant drugs that are widely used for treatment of depression and anxiety. SSRIs are considered to be very safe with favorable side effect profile, hence many patient after coronary events who suffers from behavioral and emotional disturbances are treated with those drugs. However there are several reports that SSRIs can inhibit platelet function and increase bleeding tendency particularly in concomitant administration with aspirin. The proposed mechanism is blocking of platelets serotonin reuptake that result in platelet dysfunction.

Fluvoxamine - is a member in the SSRI family and a potent inhibitor of the CYP2C19. Theoretically fluvoxamine should have two conflicting effects on the response to clopidogrel. Pharmacokinetically it is expected to decrease the clopidogrel responsiveness due to inhibition of CYP2C19 and reduction in the production of the active metabolite. On the other hand "pharmacodynamically" fluvoxamine may directly inhibit platelet aggregation due its effect on serotonin reuptake, thus increasing the effect of clopidogrel. Other SSRIs that do not interact with the CYP2C19 such as citalophram are expected to have only pharmocodynamic effect on platelet aggregation.

Although both clopidogrel and SSRIs are widely used in the last decade and concomitant treatment is quite common, no data is available about in influence of the interaction between those drugs on platelet function and on clinical events. The net effect of fluvoxamine and other SSRIs on platelet function in the presence of clopidogrel is not known.

The aim of the investigators study is to assess the effect of two SSRIs fluvoxamine and citalophram on platelet aggregation and to test the effect of these drugs on the laboratory response to clopidogrel, in healthy individuals.

Study design: randomized, double blinded, controlled crossover trial. Primary study end point: Change in % platelet aggregation and VASP phosphorylation after treatment with clopidogrel + fluvoxamine or clopidogrel + citalophram as compared to each drug alone.

Condition Intervention Phase
Drug Interactions Between Clopidogrel and Serotonin Reuptake Inhibitors Drug: fluvoxamine Drug: citalopharm Phase 1

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Treatment
Official Title: Impact of Citalopharm and Fluvoxamine on Platelet Response to Clopidogrel, a Randomized, Double-blind, Crossover Trial

Resource links provided by NLM:

Further study details as provided by RONNY ALCALAI, Hadassah Medical Organization:

Primary Outcome Measures:
  • Platelet reactivity in response to clopidogrel [ Time Frame: 12 months ]
    We will assess response to clopidogrel by two methods: 1. % change in platelet aggregation using light transmission aggregometry with ADP as agonist. 2. % of change in VASP phosphorylation - measure of activation of the platelet P2Y12 receptor (targeted by clopidogrel). The response clopidogrel will be measured after administration of clopidogrel and after co-administration of clopidogrel and each of the study drugs (fluvoxamine and citalophram). Statistical analysis will be performed to assess differences in platelet function between the different drug treatments.

Enrollment: 15
Study Start Date: September 2011
Study Completion Date: December 2012
Primary Completion Date: December 2012 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: fluvoxamine Drug: fluvoxamine
Fluvoxamine 100mg daily, 7 days
Active Comparator: citalopharm Drug: citalopharm
Citalopharm 20mg daily, 7 days


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Ages Eligible for Study:   18 Years to 60 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy volunteers

Exclusion Criteria:

  • Bleeding tendency
  • Hypersensitivity to study drugs
  Contacts and Locations
No Contacts or Locations Provided
  More Information

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: RONNY ALCALAI, Director, Cardiac Care Unit, Mt. Scopus, Hadassah Medical Organization
ClinicalTrials.gov Identifier: NCT01396720     History of Changes
Other Study ID Numbers: 0255-HMO-CTIL
First Submitted: July 14, 2011
First Posted: July 19, 2011
Last Update Posted: January 29, 2013
Last Verified: January 2013

Additional relevant MeSH terms:
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
Anti-Anxiety Agents
Tranquilizing Agents
Central Nervous System Depressants
Psychotropic Drugs
Serotonin Uptake Inhibitors
Neurotransmitter Uptake Inhibitors
Membrane Transport Modulators
Serotonin Agents
Antidepressive Agents, Second-Generation
Antidepressive Agents
Cytochrome P-450 CYP1A2 Inhibitors
Cytochrome P-450 Enzyme Inhibitors
Enzyme Inhibitors
Cytochrome P-450 CYP2C19 Inhibitors