Anticholinergic drug use and bowel function in nursing home patients

We sought to measure the relationship between the use of anticholinergic drugs and bowel dysfunction in nursing home patients.

The study population consisted of 800 residents (average age, 84.7 years; range, 65 to 105 years) from 12 intermediate-care facilities in Massachusetts. Patient characteristics and actual medication use were documented during a 1-month observation period. Neuropsychological and functional testing was performed on all residents receiving psychoactive medications. Constipation was assessed by measuring the frequency of laxative use.

Laxatives were used daily by 74% of residents; 45% received more than one laxative a day. After adjusting for potential confounding by logistic regression modeling, we found that daily laxative use was significantly more common in residents taking highly anticholinergic antidepressants such as amitriptyline (odds ratio, 3.12), diphenhydramine (odds ratio, 2.18), highly anticholinergic neuroleptics such as thioridazine (odds ratio, 2.01), and in the very old (odds ratio, > or = 85 years = 2.23). Gender, decreased functional status, impaired cognitive function, and the use of benzodiazepines or antiparkinsonian agents were not associated with increased use of laxatives.

A strong association exists in institutionalized elderly between the use of specific anticholinergic medications and constipation, as reflected in the increased use of laxatives. This effect was not seen with nonanticholinergic sedatives, nor was it explained by the patients' cognitive or functional status. These drugs may be responsible for substantial iatrogenic effects on bowel function in elderly patients.