Management of Anticholinergic Effects
Immediate Management
- The American College of Medical Toxicology recommends immediately discontinuing all offending medications and administering physostigmine 0.5-1 mg IV in adults (0.01-0.02 mg/kg in children) to reverse both central and peripheral anticholinergic effects within minutes 1, 2
- Central manifestations of anticholinergic toxicity include agitated delirium, confusion, hallucinations, disorientation, anxiety, and seizures, while peripheral manifestations include tachycardia, mild hyperthermia, mydriasis, dry mucous membranes, hot/dry/erythematous skin, hypoactive bowel sounds, and urinary retention 1, 2
- The treatment protocol involves stopping all anticholinergic medications immediately, including first-generation antihistamines, muscle relaxants, overactive bladder agents, tricyclic antidepressants, phenothiazines, and anticholinergics used for antipsychotic side effects, and providing supportive care with benzodiazepines for agitation 1, 2
Chronic Anticholinergic Burden Management
- The American Geriatrics Society recommends a stepwise deprescribing algorithm, starting with discontinuing anticholinergic medications used solely to manage side effects of other drugs, then reducing doses to the minimum effective level, switching to alternatives with lower anticholinergic activity, and using gradual tapering rather than abrupt discontinuation to avoid withdrawal symptoms or rebound worsening 1
- For antipsychotics, switching from high anticholinergic agents to those with lower anticholinergic burden while remaining within therapeutic range is recommended 1
- For antidepressants, switching from tertiary amine tricyclics to secondary amines with reduced anticholinergic effects is recommended 1
- For overactive bladder, switching from anticholinergic agents to beta-3 adrenergic receptor agonists, which carry less risk of urinary retention, is recommended 1
Special Population Considerations
- Older adults are particularly vulnerable to anticholinergic adverse effects due to baseline cognitive impairment and reduced physiologic reserve, and strongly anticholinergic medications should be avoided entirely 2, 3
- In elderly patients with Alzheimer's disease receiving antipsychotics, avoiding benztropine or trihexyphenidyl entirely is recommended 1, 2
- Deprescribing anticholinergic medications can prevent falls, reverse cognitive decline, and improve functional status and activities of daily living scores in elderly patients 3
Common Pitfalls to Avoid
- The American Academy of Allergy, Asthma, and Immunology recommends avoiding the AM/PM dosing strategy, as first-generation antihistamines dosed at bedtime still cause significant daytime drowsiness and performance impairment due to prolonged half-lives 4
- Anticholinergic effects can persist longer than plasma levels of the parent compound, so symptoms may continue even after drug levels decline 4