Idazoxan, an alpha‐2 antagonist, and L‐DOPA‐induced dyskinesias in patients with Parkinson's disease

AbstractDyskinesia is a frequent and disabling side effect in patients with Parkinson's disease treated with chronic dopatherapy. Preclinical data in the 1‐methyl‐4‐phenyl‐1,2,3,6,‐tetrahydropyridine (MPTP) monkey suggest that alpha‐2 antagonists may reduce dihydroxyphenylalanine (L‐DOPA)‐induced dyskinesia. We assessed, in a pilot randomised placebo‐controlled study, the effects of single oral doses (10 mg, 20 mg, and 40 mg) of idazoxan, an alpha‐2 antagonist, on motor parkinsonian disability and L‐DOPA‐induced dyskinesia following an acute oral challenge of L‐DOPA in 18 patients with Parkinson's disease. The severity of L‐DOPA‐induced dyskinesia improved after 20 mg idazoxan pretreatment, while there was no concommittant deterioration in the antiparkinsonian response to L‐DOPA. These results suggest that blocking alpha‐2 receptors in patients with Parkinson's disease might improve L‐DOPA‐induced dyskinesia without the cost of a return of parkinsonian symptomatology. Further studies are required to assess whether this property could have potential therapeutic applications in the long‐term management of dyskinetic patients with Parkinson's disease. © 2001 Movement Disorder Society.