Mirtazapine in L-dopa-induced dyskinesias

Mirtazapine is a novel antidepressant with a pharmacologic profile (alpha-2 antagonist, 5HT-(1A) agonist, and 5HT-(2) antagonist) that renders it potentially useful for l-dopa-induced dyskinesias. Drugs with 5HT-(1A) agonistic activity, such as buspirone and tandospirone, have been reported to be effective in reducing l-dopa-induced dyskinesias. Furthermore, 5HT-(2) antagonism may, by reducing substantia nigra pars reticulata hyperactivity, play a role in the improvement of Parkinsonian symptoms and l-dopa-induced dyskinesias, as has been observed with ritanserin, a 5HT-(2) antagonist. Alpha-2 antagonists, such as idazoxan, have recently also been reported to improve l-dopa-induced dyskinesias. The authors investigated the antidyskinetic properties of mirtazapine by designing an open-label study of 20 Parkinsonian patients with l-dopa-induced dyskinesias. Mirtazapine proved to be moderately effective in reducing l-dopa-induced dyskinesias, either alone or in association with amantadine. Mirtazapine may be of use in patients who do not respond or are intolerant to amantadine.