Olanzapine-induced parkinsonism associated with smoking cessation

Purpose. The case of a patient taking high-dosage olanzapine who experienced parkinsonism after smoking cessation is reported. Summary. A 73-year-old Caucasian woman with a recent diagnosis of Parkinson disease and a history of chronic obstructive pulmonary disease, hyperlipidemia, chronic osteoarthritis, and hypothyroidism was hospitalized for altered mental status, weakness, and ambulatory dysfunction. The diagnosis of Parkinson disease was made approximately four months prior. Despite initiation of carbidopa-levodopa, the 'patient's symptoms did not improve, and her mental and physical status declined. The patient was taking olanzapine 30 mg daily for bipolar disorder and had a 40-pack-year history of smoking, but she quit smoking approximately four months before this hospitalization. The results of a neurologic evaluation suggested that the patient did not have Parkinson disease but was possibly experiencing olanzapine toxicity secondary to smoking cessation. Carbidopa-levodopa was discontinued. Psychiatry was consulted, and a monthlong cross-taper to discontinue olanzapine and initiate aripiprazole with a target dosage of 20 mg daily was recommended. During the course of therapy, the patient's level of alertness and bradykinesia improved. Overall, it was noted that her extrapyramidal symptoms were gradually improving; two days before hospital discharge, she was noted to have no definite remaining evidence of parkinsonism. In this case, use of the Naranjo et al. adverse-drug-reaction probability scale and the drug interaction probability scale indicated that the adverse effects were probably related to the interaction between smoking and olanzapine. Conclusion. A 73-year-old woman receiving high-dosage olanzapine for bipolar disorder developed parkinsonism after smoking cessation.