Millions of consumers take antacids to relieve symptoms of acid reflux and other digestive discomforts. Now there's a warning about one particular type of antacid that could be in your medicine chest.
A huge study by researchers at Stanford and Houston Methodist Research Institute found that adults who use what are called proton pump inhibitors (PPI) are between 16% and 21% more likely to experience a heart attack.
Several of these drugs are by prescription only but there are plenty that are sold over-the-counter. They include Nexium, Prilosec, and PrevAcid.
The good news is not all antacid products carry this risk, the researchers say. For example, antacids that are H2 blockers were not shown to have any increased heart attack risk. Brand name examples of H2 antacids are Zantac and Tagamet.
Damages blood vessels
The findings are reported in the journal PLOS ONE and follow a 2013 report in which scientists showed how -- at a molecular level -- PPIs might cause long-term cardiovascular disease and increase a patient's heart attack risk. Dr. John Cooke, a senior author of the PLOS ONE article, says the earlier work showed how PPIs can damage the Teflon-like lining of blood vessels.
"That observation led us to hypothesize that anyone taking PPIs may be at greater risk for heart attack," Cooke said. "Accordingly, in two large populations of patients, we asked what happened to people who were on PPIs versus other medications for the stomach."
When they looked at data from patients who primarily received PPI drugs for their acid reflux, they found a higher rate of heart attacks, even among those who had no history of heart disease.
In today's highly stressful world antacids are huge sellers and the Food and Drug Administration (FDA) estimates 1 in 14 Americans uses or has used proton pump inhibitor drugs. In 2009, PPIs were the third-most taken type of drug in the U.S., and are believed to account for $13 billion in annual global sales.
While acid reflux is one of the most common complaints, doctors prescribe PPIs to treat a wide range of disorders, including infection by the ulcer-causing bacterium Helicobacter pylori, Zollinger-Ellison syndrome, and Barrett's esophagus.
PPIs are formulated in a variety of chemical forms, but the generic name always ends with the suffix "-prazole," like omeprazole or lansoprazole.
Under the microscope
PPIs have literally been under the microscrope in recent years because of suspected health risks. In 2011 the FDA warned that PPIs might cause low serum magnesium levels if taken for prolonged periods of time, in most cases, longer than one year.
In terms of heart risks, the researchers say it was first thought these drugs only posed a risk to a small number of patients - those who already had coronary artery disease who were using the anti-platelet drug clopidogrel to prevent future heart attacks.
"Investigators originally assumed this was due to a drug-drug interaction between these compounds, and the FDA went so far as to release a warning about their concomitant use," said Stanford vascular medicine specialist Nicholas Leeper, one of the study's authors.
Cooke says at the very least, their study shows the need for closer examination of even the possibility of a link between these popular drugs and increased heart risk.
"Our report raises concerns that these drugs -- which are available over the counter and are among the most commonly prescribed drugs in the world -- may not be as safe as we previously assumed," Cooke said.
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