An Atypical Case of Neuroleptic Malignant Syndrome Associated With Ciprofloxacin and Quetiapine.

A 29-year-old male presented to the emergency department with complaints of shortness of breath and numbness in bilateral upper and lower extremities that started a few hours prior to arrival. On physical examination, the patient was afebrile, disoriented, tachypneic, tachycardic, and hypertensive with generalized muscle rigidity. Further investigation revealed that the patient had recently been prescribed ciprofloxacin and restarted on quetiapine. The initial differential diagnosis was acute dystonia, and subsequently, the patient was placed on fluids, lorazepam, diazepam, and later benztropine. The patient's symptoms began to resolve, and psychiatry was consulted. Given the patient's autonomic instability, altered mental status, muscle rigidity, and leukocytosis, psychiatric consultation revealed an atypical case of neuroleptic malignant syndrome (NMS). It was postulated that the patient's NMS was caused by a drug-drug interaction (DDI) between ciprofloxacin, a moderate cytochrome P450 (CYP) 3A4 inhibitor, and quetiapine, which is primarily metabolized by CYP3A4. The patient was then taken off quetiapine, admitted overnight, and discharged the next morning with complete resolution of his symptoms along with a prescription for diazepam. This case highlights the variable presentation of NMS and the need for clinicians to consider DDI when managing psychiatric patients.