Anticholinergics (Benztropine, Atropine, Oxybutynin)

Anticholinergics are drugs that block acetylcholine at muscarinic receptors, causing dry mouth, blurred vision and photophobia, urinary retention, constipation, tachycardia and decreased sweating. That shared action tells you who should avoid them: clients with angle-closure glaucoma, urinary retention or BPH, GI obstruction or paralytic ileus, tachydysrhythmias, or myasthenia gravis. In older adults they cause confusion, delirium, falls and urinary retention, so strongly anticholinergic drugs are on the Beers list, and the burden adds up with tricyclics, first-generation antihistamines and phenothiazines. Each drug has its own job. Benztropine treats Parkinson's tremor and rigidity and acute dystonia from antipsychotics, but it does not treat tardive dyskinesia and may worsen it. Atropine treats symptomatic bradycardia and organophosphate poisoning. Oxybutynin treats overactive bladder, so assess for urinary retention first. Toxicity looks hot, dry and flushed, with dilated pupils, tachycardia, urinary retention, agitation and delirium. Teach sugarless gum or ice chips, fluids and fiber, sunglasses, avoiding overheating, voiding before a dose, and reporting inability to urinate or eye pain.