Development of Parkinsonism following exposure to aripiprazole: two case reports
Development of Parkinsonism following exposure to aripiprazole: two case reports
Introduction: Aripiprazole is a novel atypical neuroleptic used in the treatment of psychosis. A few recent studies have demonstrated an association between the use of aripiprazole and an exacerbation of Parkinsonism, although this relationship is poorly defined. To our knowledge, this is the first case series describing an onset of Parkinsonism in patients without prior history of Parkinson’s disease following aripiprazole treatment.
Case presentation: We describe two patients, ages 69 and 58, who developed cardinal features of Parkinson’s disease shortly after receiving aripiprazole. Both patients were male veterans with a history of bipolar disorder treated with aripiprazole. They initially presented with asymmetric arm tremor, and subsequently developed rigidity, bradykinesia, and postural instability. On examination, they were found to be at a Hoehn and Yahr stage of 2.5 for their Parkinsonism.
Conclusions:
While aripiprazole has been associated with infrequent extrapyramidal side effects, these cases raise concerns that its chronic exposure may lead to D2 receptor hypersensitivity and/or dysfunction and subsequent development of a syndrome mimicking idiopathic Parkinson’s disease. With the available atypical neuroleptics becoming widely used in treating psychotic symptoms associated with a broad range of disorders, we advise closer monitoring due to their potential for inducing Parkinsonism.
Introduction
Aripiprazole is one of the recently introduced atypical antipsychotics (AAs) used in the treatment of psychosis related to schizophrenia [1], depression [2], bipolar disorder [3], and Parkinson’s disease (PD) [4]. Welldocumented side effects associated with the use of aripiprazole include insomnia, anxiety, headaches, nausea, vomiting, and somnolence [5]. As with other AAs, aripiprazole has been associated with fewer extrapyramidal side effects (EPS) that are thought to arise from a greater than 80% D2 receptor occupancy rate in the striatal area of the basal ganglia [6]. The differential EPS profile of aripiprazole can be attributed to its unique mechanism of action as a partial agonist at dopamine D2 and serotonin 5-HT1a receptors. Additionally, the drug functions as an antagonist at serotonin 5-HT2a receptors. Such mechanism of action is believed to stimulate dopamine release via a feedback loop in the basal ganglia [6]. Given its unique pharmacologic profile, aripiprazole may have a greater potential for worsening Parkinsonism than other AAs.
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