Widely used heartburn and ulcer drugs can make people more susceptible to pneumonia, probably because they reduce germ-killing stomach acid, Dutch researchers found in a study of more than 300,000 patients.
The highest risks occurred with more powerful acid-fighting drugs called proton pump inhibitors, which are sold in the United States under such brand names as Nexium, Prevacid and Prilosec. Over nearly three years, users of these drugs faced almost double the risk of developing pneumonia compared with former users.
Users of another class of acid-fighting drugs that includes cimetidine and famotidine — sold in the United States as Tagamet and Pepcid — also faced an elevated risk.
The study was led by researcher Robert J.F. Laheij at University Medical Center St. Radboud in Nijmegen, Netherlands, and appears in Wednesday's Journal of the American Medical Association.
The acid in normal stomach fluids generally kills harmful bacteria; suppressing it with drugs to treat heartburn and ulcers may make the body more hospitable to such germs, which may then infect the lungs and cause pneumonia, the researchers said.
These heavily promoted medicines are among the most widely prescribed drugs worldwide, with almost $13 billion in sales in 1998 alone, according to a JAMA editorial. Millions of Americans take these drugs, which are heavily advertised in "ask your doctor about ..." TV commercials.
Older patients and those with asthma and other chronic lung ailments are especially vulnerable to pneumonia. In light of the latest findings, the researchers said such patients should use these medicines "only when necessary and with the lowest possible dose."
Among the 364,683 patients whose medical records were studied, 5,551 cases of pneumonia were diagnosed — 185 of them in people taking acid-suppressing drugs.
The researchers said their findings translate to about one case of pneumonia for 226 patients treated with the more potent acid-fighting drugs and one case per 508 patients treated with the other drugs.
Users of the more potent drugs were 89 percent more likely than former users to develop pneumonia. Patients using the less potent drugs were 63 percent more likely to develop pneumonia than former users of those drugs.
Nevertheless, the findings are reassuring because the apparent increase in the risk of pneumonia was small, said Dr. James Gregor of the University of Western Ontario.
Moreover, the study does not actually prove that the drugs cause pneumonia, said Gregor, who wrote the JAMA editorial and was not involved in the research. Regardless of which medication a patient is taking, heartburn, or acid reflux disease, can cause a person to accidentally inhale regurgitated stomach acid, increasing the risk of pneumonia, he said.
By Lindsey Tanner