Amisulpride - A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy in the management of schizophrenia

Amisulpride is a substituted benzamide. It is a dopamine antagonist with high selectivity for dopamine D-2 and D-3 receptors. In high doses, amisulpride exhibits dopaminergic blocking activity similar to that induced by classical antipsychotic agents, whereas in low doses it appears to facilitate dopaminergic transmission. In well controlled studies of patients with primary negative symptoms of schizophrenic who had high negative and low positive symptoms scores, amisulphide 50 to 300 mg/day was more (2 to 12 mg/day) in less rigorous trials which included patients with negative symptoms of schizophrenia. At higher dosages (600 to 1200 mg/day), amisulpride exhibits efficacy similar to that of haloperidol 5 to 40 mg/day or flupenthixol 25 mg/day in patients with positive symptoms of schizophrenia. In low and high dosages, amisulpride is generally well tolerated. Extra-pyramidal symptoms (EPS) induced by amisulpride can occur at both low and high dosages and are dose-dependent. Symptoms are generally mild or moderate. In comparative trials, amisulpride caused an incidence of EPS similar to that with placebo and lower than that caused by haloperidol, flupenthixol or fluphenazine. Neuroendocrine adverse events were reported rarely with low-dose amisulpride and at similar incidences with amisulpride greater than or equal to 600 mg/day and haloperidol 16 mg/day. Insomnia and excitation occurred rarely. As classical antipsychotic drugs are not generally effective in reducing negative symptoms of schizophrenia, amisulpride should be considered a promising agent in the management of patients with schizophrenia who have predominantly negative symptoms. While amisulpride does not offer superior efficacy over classical antipsychotic in the management of patients with positive symptoms of schizophrenia, its lower potential for causing EPS justifies consideration of its use, especially in patients intolerant of classical antipsychotics.