Adverse Drug Events Suspected Neuroleptic Malignant Syndrome During Quetiapine-Clozapine Cross-Titration

Neuroleptic malignant syndrome (NMS) is a physiologic phenomenon that has been associated with the use of both first- and second-generation antipsychotics resultant to their ability to block dopamine blockade in the basal ganglia and hypothalamic regions of the brain. The typical reaction involves the presentation of muscle rigidity, changes in mental status, temperature elevation, labile blood pressure, and elevations in creatinine kinase and white blood cell counts. The reaction is most often reported early in the course of therapy but is well documented to have the potential to occur at any point in time. Untreated NMS can be fatal, often from secondary causes such as deep venous thrombosis and pulmonary embolism. Treatment involves immediate discontinuation of the offending agent, supportive therapy of clinical symptoms, and may include the use of the skeletal muscle relaxant, dantrolene sodium, or the dopaminergic agents bromocriptine or amantadine. In this case, we present a patient who developed symptoms of NMS during the cross-taper and conversion from quetiapine to clozapine. The patient was treated for NMS; however, his clinical diagnosis was never able to be definitively determined as he was initially evaluated for septicemia and later treated for suspected bacterial infection with antibiotics, and clozapine-associated side effects cannot be ruled-out as a contributing source to the clinical presentation. The estimated Naranjo Scale score for this case report is 3. Keyword