A heightened use of the pain-reducing drug, acetaminophen, may increase the risk of developing asthma or chronic obstructive pulmonary disease (COPD), according to a study from a group of international researchers.1
One Theory: Oxidation?
The research did not conclude that acetaminophen was a direct cause of COPD, but that there was an association with the drug's daily use and incidence of the disease. Still, the investigators in the international study have a theory for the apparent link. "Oxidative stress may increase the risk of asthma, contribute to asthma progression, and decrease lung function," they wrote in the May 1 issue of the American Journal of Respiratory and Critical Care Medicine. "Previous research suggests that use of acetaminophen, which is hypothesized to reduce antioxidant capacity in the lung, is associated with an increased risk of asthma."
According to the study team, previous animal studies suggested that acetaminophen could deplete a beneficial antioxidant found in the airway of the lung, which could ultimately damage lung tissue.
Antioxidants are beneficial molecules in the body that may protect cells from damage caused by unstable molecules known as free radicals. Antioxidants can help stabilize oxidants (free radicals) and may prevent the damage they may have caused otherwise.2
Leading Cause of Death
Chronic obstructive pulmonary disease is the fourth leading cause of death in the United States. It's a lung disease that makes it hard to breathe because the airways are partially obstructed. As a result, the airways and air sacs of the lungs lose their shape and become floppy, causing airway restriction. The most common cause of COPD is cigarette smoking.3 However, it can evolve in people with pulmonary hypertension4 or co-exist in those with pulmonary fibrosis, for example.5
Acetaminophen/COPD Link Assessed
In the study, Tricia McKeever, PhD, a research fellow in the Division of Epidemiology and Public Health at the University of Nottingham in the UK and her colleagues gathered information from records of more than 13,000 patients who took part in the Third National Health and Nutrition Survey (NHAMES III), a U.S. study that ran from 1988 to 1994. Participants in the survey were asked about certain health habits, such as whether they had taken aspirin, acetaminophen, and ibuprofen during the previous month. They were then classified as "never users", "occasional users", "regular users", and "daily users".
After measuring the rate of acetaminophen usage in the NHAMES III study and comparing it to the incidence of COPD cases, McKeever and her colleagues found that "increased use of acetaminophen had a positive-dose-dependent association with COPD and an inverse association with lung function." (Lung function decreased with higher doses of acetaminophen).
Other Data
The investigators found that nearly 7 percent of the patients in the U.S. study had been diagnosed with asthma, and nearly 12 percent had contracted COPD. Almost 3 percent had both respiratory illnesses. In terms of acetaminophen use, about 4 percent of the study participants used the drug daily, more than 8 percent used aspirin, and about 2-and-a-half percent had used ibuprofen.
A small percentage reported using all three medications in the previous month; 16 percent reported using two types of medications.
McKeever's group determined that neither aspirin nor ibuprofen use were associated with the prevalence of asthma or COPD in the study population.
"This study provides further evidence that use of acetaminophen is associated with an increased risk of asthma and COPD, and with decreased lung function," the researchers wrote. They added that the findings confirm those of previous studies.
1. McKeever TM, Lewis SA, Smit HA, Burney P, Britton JR, Cassano PA. The association of acetaminophen, aspirin, and ibuprofen with respiratory disease and lung function. Am J Respir Crit Care Med 2005 May 1;171(9):966-71. Epub 2005 Feb 25.
2. National Cancer Institute. National Institutes of Health (NIH). Antioxidants and Cancer Prevention: Questions and Answers. Available at: http://www.cancer.gov/newscenter/pressreleases/antioxidants. Accessed May 12, 2005.
3. National Heart, Lung, and Blood Institute. National Institutes of Health (NIH). What is Chronic Obstructive Pulmonary Disease (COPD)? Available at: http://www.nhlbi.nih.gov/health/dci/Diseases/Copd/Copd_WhatIs.html. Accessed May 12, 2005.
4. Barbera JA, Peinado VI, Santos S. Pulmonary hypertension in COPD: old and new concepts. Monaldi Arch Chest Dis 2000 Dec;55(6):445-9.
5. Ji R, He Q. The clinical study of pulmonary emphysema with pulmonary fibrosis. Zhonghua Jie He He Hu Xi Za Zhi 1999 Nov;22(11):666-8.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
