Successful treatment of drug-resistant cataplexy with the anticholinergic drug tropatepine

Narcolepsy type 1 is characterized by excessive daytime sleepiness and cataplexy, as well as hypocretin deficiency. Cataplexy (the loss of voluntary postural muscle tone, often in response to emotional stimuli) is one of the most disabling features and is associated with significant social impairment and risk of injury. Cataplexy is usually alleviated by antidepressants sodium oxybate and pitolisant. In this case report, we describe three patients with severe, drug-resistant cataplexy who experienced a dramatic improvement when treated with tropatepine, an anticholinergic muscarinic antagonist (commonly used to prevent neuroleptic-induced parkinsonism) after the usual treatments had failed. The single side effect was mild mouth dryness. In addition to providing a new therapeutic option for resistant cataplexy, this benefit supports a role of cholinergic muscarinic transmission in rapid eye movement sleep atonia.