What are the prescribing considerations for anticholinergic drugs in older adults?

Anticholinergic Medications in Older Adults: Prescribing Considerations

Anticholinergic medications should be avoided in older adults whenever possible due to their significant risk of adverse effects including cognitive impairment, falls, and decreased quality of life. 1

Risks of Anticholinergic Burden in Older Adults

• Anticholinergic medications are associated with significant central nervous system effects including hallucinations, agitation, confusion, and somnolence, particularly in the first few months of treatment 2
• Older adults experience a decline in acetylcholine physiology with aging, making them more susceptible to anticholinergic side effects 1
• Taking multiple medications with anticholinergic properties creates an "anticholinergic burden" that adversely affects cognition and functionality 1, 3
• The Drug Burden Index shows that drugs with strong anticholinergic properties are associated with decline in cognition, functional status, and activities of daily living scores in older patients 1
• Anticholinergic burden increases the risk of serious adverse events including injurious falls, episodes of confusion or delirium, emergency department visits, and hospitalizations 1, 4

Specific Anticholinergic Medications of Concern

• Tertiary-amine tricyclic antidepressants (TCAs) like amitriptyline have significant anticholinergic effects and are considered potentially inappropriate medications for older adults according to the American Geriatrics Society Beers Criteria 1, 5
• First-generation antihistamines such as diphenhydramine have strong anticholinergic effects and should be avoided in older adults 1
• Muscle relaxants like cyclobenzaprine have anticholinergic properties and are poorly tolerated in older adults 1
• Overactive bladder agents such as oxybutynin have strong anticholinergic effects and should be used with caution in the frail elderly 1, 2
• Paroxetine is associated with more anticholinergic effects than other SSRIs and should not be used in older adults 1

Prescribing Algorithm for Anticholinergic Medications in Older Adults

1. First, identify all medications with anticholinergic properties in the patient's regimen 4, 3

   • One-third to one-half of medications commonly prescribed for older people have anticholinergic activity 4
   • Consider using an Anticholinergic Drug Scale to guide clinical decision-making 6

2. Assess the cumulative anticholinergic burden 1, 3

   • Consider the number, dose, and degree of anticholinergic activity of all medications
   • Evaluate the patient for existing signs of anticholinergic toxicity (dry mouth, constipation, urinary retention, blurred vision, cognitive impairment)

3. Consider alternatives with lower anticholinergic activity 1, 5

   • For depression: SSRIs like citalopram, escitalopram, and sertraline have more favorable adverse effect profiles than TCAs 1, 5
   • For pain: non-anticholinergic analgesics should be considered before TCAs 5
   • For allergies: second-generation antihistamines have fewer anticholinergic effects 1

4. If anticholinergic medication must be used 2

   • Start with the lowest effective dose (e.g., for frail elderly, oxybutynin should be started at 2.5 mg two or three times a day rather than the standard adult dose) 2
   • Monitor closely for adverse effects, particularly in the first few months 2
   • Consider dose reduction or discontinuation if anticholinergic side effects occur 2
   • Use for the shortest duration possible 7, 8

5. Implement deprescribing strategies 7, 8

   • Regular medication reviews by pharmacists can effectively reduce anticholinergic burden 7
   • Hospital stays may provide an opportunity to address anticholinergic burden through medication review and deprescribing 8

Special Considerations

• Use anticholinergic medications with extreme caution in patients with pre-existing dementia, as they may worsen cognitive impairment 2, 4
• Avoid anticholinergics in patients taking cholinesterase inhibitors, as they have opposing mechanisms of action 2
• Be aware of the increased risk of anticholinergic side effects when these medications are combined with alcohol or other CNS depressants 1, 2
• Consider the impact of anticholinergic medications on quality of life, particularly in terms of cognitive function and risk of falls 3, 7

By carefully evaluating the necessity of anticholinergic medications and considering alternatives with lower anticholinergic properties, clinicians can significantly reduce the anticholinergic burden and improve outcomes in older adults.