Inhibited metabolism by ketoconazole, quinidine, itraconazole, erythromycin, fluoxetine. Reduced levels by rifampicin, phenytoin, carbamazepine, alcohol. Interfered w/ medications having anticholinergic activity. Synergistic activity w/ succinylcholine, other neuromuscular blockers or cholinergic agonists, β-blockers. Combination w/ medicinal products prolonging QTc interval eg, class IA & III antiarrhythmics, certain antidepressants (eg, citalopram, escitalopram, amitriptyline), other antipsychotics (eg, phenothiazine derivatives, sertindole, pimozide, ziprasidone), certain antibiotics (eg, clarithromycin, erythromycin, levofloxacin, moxifloxacin).