A series of studies questions the widespread use of popular acid-blocking medications, concluding that the drugs slightly, but significantly, increase the risk of some kinds of fractures and that they are strongly associated with an increased risk of serious intestinal infections in hospitalized patients.

The medications, called proton pump inhibitors, or PPIs, are used to treat heartburn and acid reflux disease. They are also prescribed for some people with arthritis and other conditions who require regular treatment with nonsteroidal anti-inflammatory medications (NSAIDS), like ibuprofen and naproxen, which can irritate the lining of the stomach and may lead to the development of life-threatening bleeding ulcers.

That has helped to place PPIs among the most frequently prescribed and most heavily marketed drugs in the U.S. In 2009, they were the third highest selling class of medications, accounting for $13.9 billion in sales, according to IMS Health, a company that tracks pharmaceutical spending. According to a 2009 report from the Pew Prescription Project, manufacturers spent $884 million advertising proton pump inhibitors in 2005, making them the second most highly promoted class of medications, behind antidepressants.

Too Much of a Good Thing

Proton pump inhibitors are available over-the-counter and by prescription and include omeprazole (Prilosec, Prilosec OTC), lansoprazole (Prevacid), esomeprazole (Nexium), rabeprazole (Aciphex), pantoprazole (Protonix), and dexlansoprazole (Kapidex, Dexilant).

Experts agree that these medications have become so popular, in no small part, because they work so well, clamping off the production of stomach acid nearly completely, which allows irritations in the lining of the stomach to heal.

But stomach acid also performs a variety of functions that are lost when PPIs are used. In addition to breaking down food, stomach acid also chemically changes some nutrients so they may be more easily absorbed, and it helps to kill pathogens in the gut before they can cause illness.

A growing number of studies, including five being released today as part of a special series in the Archives of Internal Medicine, suggests that PPIs are overprescribed to people who don’t benefit from such strong suppression of stomach acid, and that this overuse may come with serious health consequences.

An Increase in Infections

“We’d thought for many years that acid-suppressing medications were very safe,” says Michael D. Howell, MD, who practices in the intensive care unit at Beth Israel Deaconess Hospital, in Boston. “I don’t think we can view these as completely safe medications anymore.”

Dr. Howell and his team tracked all patients 18 years and older who were admitted to Beth Israel for at least three days over the course of four years – a total of 101,796 cases.  About 60 percent of these patients were put on some kind of acid-suppressing medication while they were in the hospital.

They found that patients who had been prescribed acid blockers had an increased risk of contracting an intestinal infection caused by Clostridium difficile bacteria.

In recent years, C. diff infections, as they are known in the medical community, have become more frequent, more severe and harder to treat as new strains emerge that are resistant to antibiotics.