Non-selective, competitive antagonist of the muscarinic acetylcholine receptor types M1, M2, M3, M4, and M5 (pKBs range from 8.9-9.8); increases firing of the sinoatrial node and conduction through the atrioventricular node of the heart, opposes the actions of the vagus nerve, blocks acetylcholine receptor sites, and decreases bronchial secretions.