Synapse
⌘+K
Synapse
PulseExploreJournal ClubResearchersJournals
Instagram
HomeJournal ClubExplore
September 16, 2026Journal of the American College of CardiologyOpen Access

Influence of Omeprazole on the Antiplatelet Action of Clopidogrel Associated With Aspirin

View Full Paper
Ask AI
Bookmark
Share

Why the study?

In an observational study, clopidogrel activity on platelets was diminished in patients receiving proton pump inhibitors, prompting evaluation of the influence of omeprazole on clopidogrel efficacy.

Population

124 consecutive patients undergoing coronary artery stent implantation

Comparison

Omeprazole (20 mg/day) vs placebo

Design

Double-blind placebo-controlled randomized trial

Follow-up

7 days

Key result

Omeprazole significantly decreased the antiplatelet effect of clopidogrel, resulting in a higher mean platelet reactivity index at 7 days compared to placebo (51.4% vs 39.8%; p < 0.0001).

Authors

MGMartine GilardJCJean‐Christophe CornilyGGGrégoire Le Gal

Discussion

Loading...

Member takes

Key expert perspectives

Captured external expert commentary on this paper, strongest first. Original sources are linked where available.

JDJeremiah DeptaCardiologist, Washington University in St. Louis

“The data on which the FDA warning was based came mostly from laboratory assays of platelet function. Preliminary results from a randomized, controlled clinical trial with hard end points show that, for the time being, we should not change the way we manage patients.”

Washington University in St. LouisNews Coverage
DBDeepak BhattChief of cardiology, VA Boston Healthcare System

“Although we should not take such warnings lightly, we also should not be alarmed. The data on which the FDA warning was based came mostly from laboratory assays of platelet function.”

VA Boston Healthcare SystemNews Coverage

Overview

Randomized double-blind trial demonstrates omeprazole significantly blunts clopidogrel antiplatelet response in stented cardiac patients, indicating a critical drug interaction.

Key Points

  • To determine whether coadministration of omeprazole diminishes the antiplatelet effect of clopidogrel in patients receiving dual antiplatelet therapy after coronary stent implantation.
  • Randomized, double-blind, placebo-controlled trial including 124 patients receiving aspirin (75 mg/day) and clopidogrel (300 mg loading, then 75 mg/day) following coronary stent placement.
  • Patients were randomized to receive either omeprazole (20 mg/day, n=62) or placebo (n=62) for 7 days.
  • Platelet reactivity was evaluated on day 1 and day 7 using vasodilator-stimulated phosphoprotein (VASP) phosphorylation via flow cytometry to calculate platelet reactivity index (PRI).
  • Baseline mean PRI VASP was equivalent on day 1 between groups: 83.2% in the omeprazole group versus 83.9% in the placebo group (p=0.72).
  • By day 7, the antiplatelet efficacy of clopidogrel was significantly impaired with omeprazole, resulting in a mean PRI VASP of 51.4% versus 39.8% with placebo (mean difference 11.6%, p<0.0001).

Study Design

Type

RCT (n=124)

Blinding

Double-blind

Randomization

randomized

PICO

P
Population
124 consecutive patients undergoing coronary artery stent implantation receiving aspirin and clopidogrel, followed for 7 days.
I
Intervention / Comparator
Omeprazole vs Placebo (20 mg/day)
O
Primary Outcome
Platelet reactivity index (PRI) value at the 7-day treatment period, p=< 0.0001

Main Result

Absolute Event Rate: 51.4% vs 39.8%

p-value: p=< 0.0001

Limitations

  • The clinical impact of these results remains uncertain

Cite This Study

Gilard et al. (2008) conducted an RCT in Coronary artery stent implantation (n=124). Omeprazole vs. Placebo was evaluated on Platelet reactivity index (PRI) value at the 7-day treatment period (p=< 0.0001). Omeprazole significantly decreased the antiplatelet effect of clopidogrel, resulting in a higher mean platelet reactivity index at 7 days compared to placebo (51.4% vs 39.8%; p < 0.0001).

synapsesocial.com/papers/6aaa09f3cd783cbb184c2d92https://doi.org/10.1016/j.jacc.2007.06.064
View Full Paper
Ask AI
Bookmark
Share

Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Effects of Omeprazole on the Antiplatelet Activity of Clopidogrel2010 · 42 citations
  2. 2Clopidogrel with or without Omeprazole in Coronary Artery Disease2010 · 1,241 citations
  3. 3Platelet reactivity of clopidogrel and aspirin with or without omeprazole in diabetes mellitus and coronary artery disease in thailand: a randomised double-blind placebo-controlled cross-over trial2025
  4. 4Comparison Between the Effect of Omeprazole and Rabeprazole on the Antiplatelet Action of Clopidogrel2010 · 27 citations
  5. 5Differential Effects of Omeprazole and Pantoprazole on the Pharmacodynamics and Pharmacokinetics of Clopidogrel in Healthy Subjects: Randomized, Placebo-Controlled, Crossover Comparison Studies2010 · 284 citations