Published this month in the journal Alimentary Pharmacology & Therapeutics, the study is the largest investigation yet into concerns of an adverse interaction between Proton Pump Inhibitors (PPIs) and the antiplatelet drug clopidogrel.

The researchers analysed data from 23 large randomised clinical trials involving more than 90,000 patients worldwide. It concluded that co-prescribing the two drugs caused no adverse effect.

"Recent studies have suggested that patients receiving clopidogrel will not get the full effect of the treatment if they are also taking PPIs," said lead author Dr Yoon Loke, of UEA's School of Medicine. "The aim of our study was to determine the actual effect of the treatment combination on cardiovascular outcomes and mortality.

"Our findings showed no evidence of any effect on overall mortality and no associated risk with the co-prescribing of these agents. It is therefore premature to impose a blanket policy of withdrawal or avoidance of PPI use in patients taking clopidogrel. Clinicians should instead re-focus on a patient's susceptibility to gastric bleeding and not lose sight of the fact that some patients with high gastrointestinal risk may genuinely benefit from PPI therapy."

Patients at risk of heart attack or stroke are routinely prescribed antiplatelet therapy to prevent harmful blood clots. Although the effectiveness of this treatment is well-documented, it can cause bleeding in the stomach, which is potentially life-threatening. Co-prescribing PPIs substantially decreases this risk.

The findings of this new meta-analysis by UEA are in direct contrast to the ongoing safety review by the US Food and Drug Administration (FDA), which has advised health professionals to avoid the concomitant use of clopidogrel and omeprazole (a PPI).

However, the FDA's findings are based on laboratory data rather than a thorough review of actual clinical outcomes in patients.

In the United Kingdom, around 100,000 patients are admitted to hospital each year with heart attack or stroke. In the United States, more than 1.5 million people per year are affected. Patients are typically treated with aspirin and/or clopidogrel, which may cause side effects such as stomach ulcers and bleeding. Proton pump inhibitors are used to prevent gastrointestinal bleeding, and these are one of the most commonly-prescribed classes of drug in the world, costing £425m in England and £7bn globally in 2006.

Note: If no author is given, the source is cited instead.

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