Intensified anticholinergic effect of TCAs, tetracyclic antidepressants, antihistamines, quinidine, amantadine, antipsychotics eg, phenothiazines, butyrophenones, disopyramide, other anticholinergics eg, tiotropium, ipratropium, atropine-like compd. Enhanced tachycardiac effects of β-adrenergic agents. Diminuted effects on GI tract w/ dopamine antagonists eg, metoclopramide.