Tiapride

Tiapride is an atypical neuroleptic which exhibits selectivity in in-vitro studies for D₂ and D₃ dopamine subtype receptors without any affinity for subtype receptors of the principal central neurotransmitters (including serotonin, noradrenaline and histamine). These properties have been confirmed in neurochemical and behavioural studies in which antidopaminergic properties have been demonstrated in the absence of sedation, catalepsy and cognitive impairment.

Tiapride is rapidly absorbed. Maximal concentration of the active substance are reached as early as within one hour.

The absolute bioavailability of the tablets is 80%.

Tiapride is mostly eliminated in the first 24 hour urine. Tiapride is mainly eliminated as the parent compound, although two metabolites have been identified. These are the N-oxide and the N-monodesethyl derivatives of the active substance. The elimination half-life is about 3 hours.

An increased incidence of breast tumours was observed in rats. This was probably due to hyperprolactinaemia as a consequence of the pharmacological action of the substance. This is probably a species-specific effect and does not constitute any particular risk to humans in therapeutic use. Other abnormalities seen in experimental animals were associated with the known pharmacological action.

A tiapride-induced reduced fertility was observed in rats due to a suppression of the estrous cycle in females and a reduced libido in males. These effects are related to the pharmacological effect of tiapride on prolactin secretion. In studies on reproductive toxicity no signs of teratogenicity were observed, however, embryotoxic effects occurred. In a study on peri-postnatal toxicity toxic effects in the offspring were seen following high doses.