Clinical experience about an unexpected adverse event during nalmefene treatment in two patients with alcohol use disorder

What is known and objective Nalmefene, a new opioid system regulator, has recently been approved for the treatment of alcohol dependence, primarily for reducing heavy drinking days. Cases description Two patients with a diagnosis of alcohol use disorder were treated with nalmefene. Both patients developed fatigue and deep sleepiness after 2 days of treatment. Only after 1 day of drug discontinuation, symptoms normalized. What is new and conclusion We have analysed symptoms' development before and after treatment discontinuation and the possible association with nalmefene therapy. This case should pinpoint our attention on this adverse event for a careful choice of anticraving therapy in patients with severe alcohol use disorder. Nalmefene is a new opioid system regulator, it is recently approved for the treatment of alcohol dependence, primarily for reducing heavy drinking days. We have analyzed adverse events in two patients treated with nalmefene and the possible association with the pharmacological therapy.