title: D2 receptor blockade by flunarizine and cinnarizine explains extrapyramidal side effects. A SPECT study.
abstract: Twenty-six patients under treatment with the calcium channel blockers flunarizine (Fz) or cinnarizine (Cz) were examined-with single-photon emission computed tomography using [123I]iodobenzamide as a ligand. The striatal dopamine D2 receptor-binding potential was determined and found to be reduced by 14 to 63% (39.5 +/- 15.0%; p < 0.0001) in patients compared with age-matched control values. This reduction was larger in 12 patients with extrapyramidal symptoms and was only slowly reversible after discontinuation of treatment. Patients treated for > 6 months had significantly larger reductions than patients treated for a shorter period. Parkinsonian symptoms were only seen in patients older than 50 years. Our findings prove a neuroleptic-like action of Fz and Cz, which seems to be the major reason for their extrapyramidal side effects. Older age and long-term treatment are predisposing factors for these effects.
authors.affiliation: Neurological University Clinic Vienna, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Brücke
authors.forename: C
authors.initials: C
authors.lastname: Wöber
authors.forename: I
authors.initials: I
authors.lastname: Podreka
authors.forename: C
authors.initials: C
authors.lastname: Wöber-Bingöl
authors.forename: S
authors.initials: S
authors.lastname: Asenbaum
authors.forename: S
authors.initials: S
authors.lastname: Aull
authors.forename: S
authors.initials: S
authors.lastname: Wenger
authors.forename: D
authors.initials: D
authors.lastname: Ilieva
authors.forename: C
authors.initials: C
authors.lastname: Harasko-van der Meer
authors.forename: P
authors.initials: P
authors.lastname: Wessely
mesh_terms: D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000188:drug therapy / Q000378:metabolism; D002936:Cinnarizine / Q000009:adverse effects* / Q000627:therapeutic use; D065127:Dopamine D2 Receptor Antagonists; D005260:Female; D005444:Flunarizine / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D065127:Dopamine D2 Receptor Antagonists; D002936:Cinnarizine; D005444:Flunarizine