A specific class of drugs used to treat chronic obstructive pulmonary disease may result in urinary problems for patients, new research finds.

The medications are in a drug class called inhaled anticholinergics. That includes treatments such as Spiriva (tiotropium), Atrovent (ipratropium bromide) and Combivent (ipratropium combined with albuterol).

Canadian researchers analyzed the medical records of 565,000 COPD patients aged 66 and older. Of these patients, 9,432 men and 1,806 women developed an inability to pass urine. Among male patients who were taking inhaled anticholinergics, the odds of developing the urinary condition were about 40% higher in those who’d been using the drugs for four weeks or less. They were 80% higher among those with enlarged prostate glands.

“Physicians should highlight for patients the possible connection between urinary symptoms and inhaled respiratory medication use to ensure that changes in urinary flow (i.e., incomplete voiding, urinary incontinence and decreased urinary flow) are reported to the physician,” the authors wrote.

The study was published Monday’s issue of the Archives of Internal Medicine. The study was conducted at St. Michael’s Hospital in Toronto.