FRIDAY, Oct. 28, 2011 (HealthDay News) -- Many Alzheimer's patients who take cholinesterase inhibitors to slow their brain disease also take drugs that counter the effects of those Alzheimer's medications, a new study says.
Clinical trials have shown that cholinesterase inhibitors such as Aricept (donepezil) have a modest impact on the functional and cognitive decline caused by Alzheimer's disease, noted the researchers at the Group Health Research Institute in Seattle.
"Cholinesterase inhibitors are today's primary therapy for slowing Alzheimer's disease," study leader Denise Boudreau said in an institute news release.
"Anticholinergic properties are often found in drugs commonly used to treat gastrointestinal disorders, allergies, urinary incontinence, depression and Parkinson's disease, and they can have negative effects on cognition and function in the elderly. There's concern that if someone is taking both types of drugs -- cholinesterase inhibitors and anticholinergic medications -- they will antagonize each other, and neither will work," she explained.
Common anticholinergic medications include Benadryl (diphenhydramine) and Ditropan (oxybutynin), which is prescribed for overactive bladders.
Boudreau and colleagues analyzed data from more than 5,600 patients aged 50 and older who had cholinesterase inhibitors prescribed to them for the first time between 2000 and 2007. Of those patients, 37 percent also took at least one anticholinergic drug and more than 11 percent took two or more anticholinergic drugs.
Among the patients who took both classes of drugs, dual use generally lasted three to four months, but one-quarter of the patients used both classes of drugs for more than a year.
The researchers also found that 23 percent of patients who received a new prescription for cholinesterase inhibitors were already using at least one anticholinergic drug, and 77 percent of those patients continued taking an anticholinergic drug after they began taking a cholinesterase inhibitor.
"It's reassuring that we did not observe an association between simultaneous use of the two types of drugs and increased risk of death or nursing home placement," Boudreau said in the release. "But concomitant use of these drugs is, at the very least, not optimal clinical practice."
The study was published online Oct. 22 in the Journal of the American Geriatrics Society.
Alzheimer's patients often have multiple health problems, which may help explain why doctors might prescribe conflicting medications for these patients, the researchers said.
The U.S. National Institute on Aging has more about Alzheimer's medications.