Anticholinergics and Antimuscarinics

Anticholinergics are a class of medications that inhibit the binding of the neurotransmitter, acetylcholine, to its receptors. Acetylcholine is released by the parasympathetic nerve fibers innervating the urinary bladder and contributes to detrusor contraction and activation of the bladder afferents. These afferent stimuli activate spinal sympathetic circuits that trigger AD. In theory, anticholinergic agents could therefore decrease afferent activation, and consequently AD.

Antimuscarinics are a group of anticholinergic agents that block muscarinic receptors from the action of acetylcholine. Muscarinic receptors play a role in parasympathetic functions including involuntary functions such as contracting smooth muscle, dilating blood vessels, and increasing heart rate. Thus, antimuscarinics work by inhibiting the functions of the parasympathetic nervous system, and subsequently decreasing AD.

Discussion

Only one study has examined the use of anticholinergics (Giannantoni et al. 1998). These authors did not observe a correlation between anticholinergic drugs and reduced incidence of AD, unless treatment resulted in detrusor areflexia.

A study by Walter et al. (2023) examined the use of antimuscarinics, specifically fesoterodine, on the management of AD. They found fesoterodine to reduce the severity and frequency of AD, as well as reduce the increase in sBP compared to baseline. However, more research should be conducted to determine the effectiveness of fesoterodine.

Conclusion

There is level 4 evidence (from 1 pre-post study) (Walter et al. 2023) that fesoterodine reduces the severity and frequency of AD.

There is level 5 evidence (from 1 observational study) (Giannantoni et al. 1998) that anticholinergics are not associated with reduced incidence of AD episodes.