Bradycardia due to biperiden

In a 38-year-old male patient suffering from a severe postzosteric trigeminal neuralgia, intravenous application of 10 mg biperiden lactate led to a long-lasting paradoxical reaction characterized by considerable bradycardia, dysarthria, and dysphagia. The heart rate was back to normal within 12 hours upon administration of orciprenaline under cardiac monitoring in an intensive care unit. Bradycardia induced by biperiden is attributed to the speed of injection and to a dose-related dual effect of atropine-like drugs on muscarine receptors.