Drugs with anticholinergic properties: a current perspective on use and safety

Introduction: Many commonly used drugs have primary or secondary anticholinergic effects contributing to adverse outcomes ranging from mild-to-severe to potentially lethal. Anticholinergic adverse effects frequently occur with medications prescribed with other intended mechanisms of action, including antihistamines, antidepressants, and antipsychotics. Anticholinergic drugs are also the principal treatments of clinical conditions, such as urinary incontinence, that tend to occur in the elderly. Older patients and those with mental illness are particularly vulnerable to the adverse neuropsychiatric effects of anticholinergics as they may already have cognitive impairment. Areas covered: Medline and Pubmed literature searches (1966 - the present) were performed using 'anticholinergic' and 'drug safety'. Abstracts were assessed and references scanned for appropriate articles. Here, the authors i) describe the neural pathways of the cholinergic system; ii) outline the main clinical uses and adverse effects of anticholinergic agents with a focus on cognitive impairment; and iii) discuss anticholinergic safety monitoring. Expert opinion: Prescribers need to be vigilant for adverse anticholinergic effects, particularly in older patients. The symptoms may range from subtle cognitive impairment to delirium and may be due to the cumulative effect of multiple medications of modest antimuscarinic activity. The Anticholinergic Drug Scale and tables listing drugs with known anticholinergic properties may help in guiding clinical decision-making to reduce anticholinergic burden.