How do you manage anticholinergic side effects in patients?

From the Guidelines

Managing anticholinergic side effects requires a stepwise approach starting with dose reduction or medication substitution whenever possible, prioritizing the use of second-generation antihistamines over first-generation antihistamines due to their lower risk of anticholinergic effects, as recommended by the most recent evidence 1. When managing anticholinergic side effects, it is crucial to consider the potential risks and benefits of medication use, particularly in high-risk populations such as the elderly.

Key Considerations

• The use of first-generation antihistamines, such as diphenhydramine, is associated with significant anticholinergic effects, including dry mouth, constipation, and urinary retention, as well as sedation and cognitive impairment 1.
• Second-generation antihistamines, on the other hand, have a lower risk of anticholinergic effects and are generally preferred for the treatment of allergic rhinitis 1.
• In patients experiencing anticholinergic side effects, supportive measures such as sugar-free candies, artificial saliva, and frequent sips of water can help manage dry mouth, while increased fluid intake, dietary fiber, and osmotic laxatives like polyethylene glycol can help manage constipation.
• Regular medication reviews using tools like the Anticholinergic Cognitive Burden Scale can help identify high-risk medication combinations and inform deprescribing decisions, particularly in older patients 1.

Management Strategies

• Dose reduction or medication substitution should be considered whenever possible to minimize anticholinergic burden.
• Alternative medications with lower anticholinergic risk should be considered in high-risk patients, such as the elderly or those with cognitive impairment, prostatic hypertrophy, or narrow-angle glaucoma.
• Physostigmine (0.5-2mg IV slowly) can be administered in monitored settings for severe anticholinergic toxicity, although this is typically reserved for life-threatening situations. By prioritizing the use of second-generation antihistamines and implementing these management strategies, clinicians can help minimize the risk of anticholinergic side effects and improve patient outcomes, as supported by the most recent evidence 1.

From the FDA Drug Label

ADVERSE REACTIONS ... The most frequent adverse experiences associated with pilocarpine hydrochloride tablets were a consequence of the expected pharmacologic effects of pilocarpine. ... In the 2 placebo-controlled studies, the most common adverse events related to drug use were sweating, urinary frequency, chills, and vasodilatation (flushing)

The management of anticholinergic side effects in patients is not directly addressed in the provided drug labels. Anticholinergic side effects are not explicitly mentioned, and the labels primarily discuss the adverse effects of pilocarpine, which is actually used to treat dry mouth (xerostomia) and has cholinergic properties.

• The labels list various adverse events associated with pilocarpine use, such as sweating, nausea, rhinitis, diarrhea, chills, flushing, urinary frequency, dizziness, and asthenia.
• However, these are not anticholinergic side effects, but rather the expected pharmacologic effects of a cholinergic drug like pilocarpine.
• Since the labels do not provide information on managing anticholinergic side effects, no conclusion can be drawn. 2 2

From the Research

Management of Anticholinergic Side Effects

To manage anticholinergic side effects in patients, several strategies can be employed:

• Reduce the use of anticholinergic drugs when possible, as suggested by studies 3, 4
• Avoid prescribing multiple medications with anticholinergic activity to minimize cumulative anticholinergic burden 5
• Select less anticholinergic drugs for medication, especially in older adults 3
• Evaluate patients' fall risk and cognitive status before prescribing drugs with anticholinergic side effects 3

Treatment of Anticholinergic Delirium

In cases of anticholinergic delirium, the following treatments can be considered:

• Physostigmine, a reversible acetylcholinesterase inhibitor, is the standard antidotal treatment 6, 7
• Rivastigmine, another acetylcholinesterase inhibitor, can be used as an alternative treatment, especially in cases where physostigmine is not available 6, 7
• Oral rivastigmine may be more effective than transdermal rivastigmine in treating anticholinergic delirium 6

Monitoring and Assessment

Regular monitoring and assessment of patients taking anticholinergic medications is crucial to minimize the risk of side effects:

• Monitor for signs of anticholinergic toxicity, such as dry mouth, constipation, blurred vision, and confusion 3, 4
• Assess patients' cognitive and functional status regularly to detect any impairments 5
• Evaluate the anticholinergic burden of medications and adjust the treatment plan accordingly 5