Certain drugs may interact with this medication. Patients should tell their doctor about all medications they take prior to starting this one. The drugs that may interact include anticholinergic drugs, calcium channel blockers, aspirin, beta-blockers, heart medications, cholinergic drugs, azole antifungals, cholinesterase inhibitors, SSRI antidepressants, amitriptyline, and non-steroidal anti-inflammatory drugs.