May increase risk of bleeding w/ warfarin & coumarins. Increased anticholinergic side effects w/ other anticholinergic drugs. Additive CNS effects w/ propoxyphene. Increased bupropion levels. May antagonise actions of centrally-acting anticholinesterases eg, donepezil, galantamine, rivastigmine, tacrine. May decrease absorption of levodopa. Increased risk of liver damage w/ alcohol. Paracetamol: Increased absorption w/ metoclopramide & domperidone. Decreased absorption w/ cholestyramine.