Neuroleptic malignant syndrome associated with olanzapine therapy: a case report

We present the case of a 42-year-old male with a history of schizophrenia who developed signs and symptoms consistent with Neuroleptic Malignant Syndrome (NMS) after 3 weeks of treatment with Olanzapine. The patient presented with hyperpyrexia, tremors, labile blood pressure, and mental status changes that had progressed over the preceding 24 h. Laboratory data revealed a metabolic acidosis and an escalating creatinine phosphokinase. Olanzapine is a relatively new atypical anti-psychotic agent first introduced in November of 1996 under the trade name of zyprexa. Olanzapine differs from typical anti-psychotic agents in that it has a lower affinity for dopaminergic receptors and binds antagonistically to serotonin receptors in the nigrostriatal pathway. These unique properties result in relatively fewer extra-pyramidal symptoms when compared to traditional anti-psychotics. Because of olanzapine's favorable side-effect profile, it has quickly gained popularity in the psychiatric community. Although NMS is a recognized complication of anti-psychotic use, there has been only one case of olanzapine induced NMS reported in the literature. The POISON-INDEX system, used by toxicologists throughout the United States, does not list NMS as a potential reaction to olanzapine. The pharmacists at our institution were also unaware that NMS was a possible complication of olanzapine. We present this case to make clinicians aware of the potential for Olanzapine induced NMS.