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.