Proton pump inhibitors (PPIs), including AstraZeneca's ($AZN) longtime blockbuster Nexium, are some of the most commonly used drugs in the world to treat heartburn. But they may also be increasing the risk of heart attack, a new study shows.
Using electronic health records to mine a wealth of data, Stanford researchers discovered a 16% to 20% increase in heart attack risk, KQED reports. "The association looks to be fairly compelling," Stanford cardiologist and senior study author Nick Leeper told the publication.
Each year, more than 113 million PPI prescriptions are filled globally, according to PLOS ONE, which published the research. That helps the drugs generate an estimated $13 billion in global annual sales.
And some of the biggest are also available over the counter--such as OTC Nexium from Pfizer ($PFE) and OTC Prilosec from Procter & Gamble ($PG). Those versions help the gastric reflux-fighters reach more than 20 million Americans, KQED notes.
Of course, the new study is not definitive; only a randomized, controlled trial, where patients receive either a PPI or placebo, can prove causation, Leeper pointed out. PPI users may be a sicker population more subject to heart disease in the first place, which could have proved a confounding variable in the new study.
It's not the first time PPIs have been flagged on safety worries, though. Prior studies have linked them with poor outcomes for people with heart disease, likely because of an interaction with Plavix (clopidogrel), a drug commonly prescribed after a heart attack, The New York Times says. And in 2011, advocacy group Public Citizen petitioned the FDA to add a black box warning--the agency's most serious--to their labels. PPI therapy for a month or more can cause patients to produce even more stomach acid when they stop taking the drug, the group argued, in effect making reflux symptoms worse.
To stay on the safe side, many doctors recommend that patients check with them about whether they really need a PPI, and their makers stressed the importance of following the meds' labels.
"Consumers should read the label and follow directions closely to understand what the medicine is used for, to ensure appropriate dosing and to avoid drug interactions," Barb Kochanowski, vice president of regulatory and scientific affairs at the Consumer Healthcare Products Association, told KQED in a statement. And if consumers do use the treatments in accordance with their labels, Nexium is "generally safe and effective," AstraZeneca added.
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