Acute Dystonia With Rhabdomyolysis Induced by Paliperidone Palmitate: A Rare Adverse Effect.

Antipsychotic medications have been well-established to potentially cause extrapyramidal side effects (EPS) including hyperkinesia, tremor, dyskinesia, dystonia, and parkinsonism. Rhabdomyolysis secondary to extrapyramidal symptoms in patients under antipsychotics is a relatively rare presentation to be observed in patients.  In this report, we present a 64-year-old female with rhabdomyolysis following a once-monthly injection of long-acting injectable (LAI) paliperidone palmitate (Invega Sustenna). The patient developed extrapyramidal symptoms one day after the paliperidone injection. She presented with acute dystonia in the form of antecollis, without any evidence of generalized myalgia or kidney involvement. Laboratory investigations demonstrated a creatine kinase (CK) level of 3239 unit/L on admission. The patient's symptoms were resolved after the administration of benztropine and cyclobenzaprine and CK levels improved after IV hydration. A high index of suspicion in the investigation of rhabdomyolysis for patients presenting with extrapyramidal symptoms being treated with long-acting injectable antipsychotics leads to prompt diagnosis, early treatment, and reduction in renal and cardiac toxicities in the aforementioned population.