Bladder contraction is produced by ACh-mediated stimulation of postganglionic parasympathetic muscarinic cholinergic receptors on bladder smooth muscle. Anticholinergics bind M2 and M3 choline receptors and prevent stimulation. This increases bladder capacity by 50 ml and decreases bladder storage pressures by 15 cm H20 1).
They are a pillar in treating neurogenic bladders. All are contraindicated in glaucoma as anticholinergics induce mydriasis. Overdosage results in the classic anticholinergic symptoms (“red as a beet, hot as a stove, dry as a rock, mad as a hatter”). Use is often limited by side effects including dry mouth, constipation, dry eyes, blurry vision, urinary retention & indigestion.
Anticholinergics may negatively impact cognition and memory 2) 3). Newer agents (tolterodine, darifenacin) have less impact on memory. Trospium, a quaternary amine, crosses the blood-brain barrier less readily than other anticholinergics and may have less negative impact 4).