Amantadine Withdrawal Can Cause Severe Altered Mental Status

Amantadine is an antiviral and anti-Parkinsonian drug primarily used to treat Parkinson's disease symptoms and certain influenza A strains. It acts as a weak non-competitive NMDA receptor antagonist and dopamine reuptake inhibitor. While mild withdrawal symptoms like anxiety or insomnia are known, the occurrence of severe altered mental status (AMS) following amantadine cessation is less frequently documented, and there is a need to highlight the potential for acute and severe neurological complications upon abrupt discontinuation.

The patient presented with acute altered mental status, characterized by severe confusion, disorientation, and agitation, which developed approximately 48 to 72 hours after the abrupt discontinuation of amantadine. Initial investigations for other causes of AMS were unremarkable, pointing towards drug withdrawal as the likely etiology. Upon re-initiation of amantadine therapy, the patient's neurological symptoms showed a remarkable and rapid improvement. The patient's mental status significantly improved within 24 hours of restarting amantadine, with a near-complete resolution of confusion and agitation observed within 48 hours, demonstrating a clear temporal relationship between drug re-administration and symptom reversal. This rapid response suggests that the severe AMS was directly attributable to amantadine withdrawal, highlighting the drug's critical role in maintaining neurological stability for this patient.