title: Risk of parkinsonism induced by flunarizine or cinnarizine: a population-based study.
abstract: OBJECTIVE
  This retrospective cohort study used a population-based dataset to test the risk for parkinsonism in patients receiving flunarizine and cinnarizine, compared with matched controls.
  
  
  METHODS
  Data were obtained from the National Health Insurance Research Dataset of Taiwan. Patients receiving flunarizine or cinnarizine for more than 1 month between 2000 and 2005 were enrolled. Exclusion criteria included receiving flunarizine, cinnarizine, or antipsychotics for more than 1 month during 1997-1999, a history of neurodegenerative diseases, and an age of less than 30 years. One matched control for each patient was selected. Each participant was followed for diagnosis of parkinsonism within a 3-year observation period. Stroke, diabetes mellitus, total prescription days, and doses of flunarizine or cinnarizine were recorded.
  
  
  RESULTS
  The study and control groups consisted of 9830 subjects. In the study group, 280 patients (2.9 %) were diagnosed with parkinsonism with a median observation period of 1.2 years, and 49 participants (0.5 %) were diagnosed in the control group with a median observation period of 1.9 years. The adjusted hazard ratio for parkinsonism among patients receiving flunarizine and cinnarizine was 5.117 (95 % CI = 3.758-6.967). Age, stroke, and diabetes mellitus were significant risk factors, but female sex and total doses of the study drugs were not.
  
  
  CONCLUSIONS
  This study demonstrates that flunarizine and cinnarizine significantly increase the risk for parkinsonism. The treatment benefits of these two agents should be balanced with this adverse effect. Physicians must look carefully for early signs of parkinsonism in patients treated with flunarizine and cinnarizine.
authors.affiliation: Department of Neurology, Sijhih Cathay General Hospital, No. 2, Ln. 59, Jiancheng Rd., Sijhih Dist, New Taipei City, 221, Taiwan.|Graduate Institute of Biomedical Informatics, Taipei Medical University, No. 252, Wu-Xing Street, Taipei, 110, Taiwan.
authors.forename: Hsiu-Li
authors.initials: HL
authors.lastname: Lin
authors.affiliation: Department of Pediatrics, School of Medicine, College of Medicine, Taipei Medical University, No. 252, Wu-Xing Street, Taipei, 110, Taiwan.|Department of Laboratory Medicine, Taipei Medical University Hospital, No. 252, Wu-Xing Street, Taipei, 110, Taiwan.
authors.forename: Hsiu-Chen
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Department of Neurology, Sijhih Cathay General Hospital, No. 2, Ln. 59, Jiancheng Rd., Sijhih Dist, New Taipei City, 221, Taiwan.
authors.forename: Yuan-Fu
authors.initials: YF
authors.lastname: Tseng
authors.affiliation: Graduate Institute of Patent, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd, Taipei City, 106, Taiwan.
authors.forename: Shih-Chang
authors.initials: SC
authors.lastname: Chen
authors.affiliation: Graduate Institute of Biomedical Informatics, Taipei Medical University, No. 252, Wu-Xing Street, Taipei, 110, Taiwan. linali@ms1.hinet.net.|Department of Information Management, National Taipei University of Nursing and Health Science, No. 365, Mingde Rd, Taipei, 112, Taiwan. linali@ms1.hinet.net.
authors.forename: Chien-Yeh
authors.initials: CY
authors.lastname: Hsu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002936:Cinnarizine / Q000009:adverse effects*; D005260:Female; D005444:Flunarizine / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020734:Parkinsonian Disorders / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D002936:Cinnarizine; D005444:Flunarizine
keywords: Cinnarizine; Drug-induced parkinsonism; Flunarizine; Health insurance research dataset; Parkinsonism