Increased AUC w/ fluoxetine. Increased mean C
max & AUC w/ potent CYP3A4 inhibitors eg, ketoconazole, itraconazole, clarithromycin, ritonavir. Increased frequency &/or severity of dry mouth, constipation, blurred vision, somnolence & other anticholinergic pharmacological effects w/ other anticholinergic/antimuscarinic agents.