Prolonged unconsciousness in perampanel overdose

Clinical experience of perampanel overdoses is markedly limited and the relevant literature is sparse. Perampanel is a novel antiepileptic drug (an amino-3-hydroxy-5-methyl-4-isoxazlepropionic acid glutamate receptor antagonist) with a long half-life, which is used for the adjunctive treatment of epilepsy. The literature available identifies a potential for prolonged unconsciousness in overdose. We report a case of prolonged unconsciousness for 14 days following a perampanel overdose of 3.5 times the maximum daily dose, requiring protracted intubation and ventilation on intensive care, with eventual complete neurological recovery. This represents the longest known period of unconsciousness with full recovery and the first reported in a perampanel naive patient. This case helps to inform decision-making in critical care, particularly the early consideration of admission and intubation. It highlights that while perampanel overdose may not initially cause systemic effects such as cardiac toxicity, it can cause protracted altered consciousness with secondary compromise requiring prolonged intensive care management.