Anticholinergics

Why are anticholinergics problematic?

Anticholinergics have long been recognised as causing symptoms such as dry mouth, constipation and urinary retention. Exposure to anticholinergic agents has also been linked to impaired cognition and physical decline. There may also be an association with falls, and increased mortality and cardiovascular events. The table below shows that anticholinergic effects are dose dependent (adapted from reference¹). Of note is, however, that there is significant inter-individual variability regarding anticholinergic dose and manifestations of signs and symptoms of toxicity, which is why it is essential to understand the patient’s perspective.

¹Sumukadas D, McMurdo MET, Mangoni AA, Guthrie B. Temporal trends in anticholinergic medication prescription in older people: repeated cross-sectional analysis of population prescribing data. Age and Ageing 2014 July 1, 2014;43(4):515-21.

Drugs with anticholinergic properties continue to be commonly prescribed to older people and those with mental illness, who are particularly susceptible to adverse effects, even at therapeutic doses.

Anticholinergic burden principles:

• Anticholinergic effect of individual drugs vary greatly between individual patients
• Anticholinergic effect of multiple drugs are accumulative
• The comparative degree of anticholinergic drugs are based partly on clinical evidence and partly on pharmacological theory

Not all drugs with anticholinergic properties may individually put patients at risk of severe adverse effects,  however when used in combination, effects may accumulate. Reducing the anticholinergic burden may result in improvements in short term memory, confusion, behaviours and delirium.

A scale or table that assigns a cumulative anticholinergic score to a patient’s prescribed medication can be used to assess Anticholinergic Burden. A number of these scoring systems are available. While this approach is valid, the overall aim is to reduce overall anticholinergic exposure as much as possible. The table below is intended to be a guide as to which areas anticholinergic burden is likely to be the highest.

Notes

This is a developing area with many disagreements between different sources. Some of this table is based on incomplete or poor evidence, or on expert opinion.. The anticholinergic effects of drugs may become better understood with time.

Some of these therapeutic areas are highly specialised (for example Parkinson’s disease and would require expert advice before considering a change

As noted here less anticholinergic alternatives often have other concerns. If an anticholinergic agent must be used, consider reducing the dose.

Notes: This is a developing area with disagreements between different sources. Some of this table is based on incomplete or poor evidence, or on expert opinion. The anticholinergic effects of drugs may become better understood with time. Some of these therapeutic areas are highly specialised (for example Parkinson’s disease) and would require expert advice before considering a change. As noted here less anticholinergic alternatives often have other concerns. If an anticholinergic agent must be used, consider reducing the dose.