The benzamide tiapride: treatment of extrapyramidal motor and other clinical syndromes.

The benzamide derivative tiapride (Tiapridex, Synthelabo) has a highly selective antagonistic effect on striatal adenylate cyclase-independent dopamine-2 receptors. Its in vitro binding affinity is especially high for dopamine receptors which have been sensitized by pre-incubation with dopamine. The involvement of altered dopamine receptor sensitivity in several extrapyramidal dys- and hyperkinesia has been hypothesized. By its high affinity for these receptors, without any affinity for other neurotransmitter receptors of the brain, tiapride is especially well suited for the treatment of movement disorders related to functional dopamine hyperactivity. Even at higher doses, tiapride does not exceed a D2-receptor occupancy of 80%, which is in accordance with the finding that tiapride rarely causes acute extrapyramidal syndromes and has, up to now, never implicated in inducing tardive dyskinesias. On the contrary, clinical studies demonstrate its excellent efficacy in neuroleptic-induced tardive dyskinesia, L-Dopa-induced dyskinesias, psychomotor agitation in geriatric patients and choreatic movement disorders. Since tiapride is not available in the USA as yet, most of the studies concerning tiapride have been carried out in Europe. In a recent study, based on objective measurements, tiapride effectively controlled choreatic movements in patients suffering from Huntington's disease (HD). Tiapride is well tolerated in daily doses between 300 and 1200 mg. Adverse events are generally rare and mild.