Methods of use and compositions of (S) (-)-amisulpride

#This invention relates to a novel composition containing optically pure (S)(−)-amisulpride or a pharmaceutically acceptable salt thereof.

#This composition possesses antipsychotic properties useful in the treatment of positive, negative, affective or cognitive symptoms of schizophrenia, dysthymia, autism, tardive dyskinesia induced by neuroleptics, Tourette disease(tics), manic or depressive symptoms in patients with bipolar disorders, sudden attacks of delirium, migraine and drug addiction while inducing therapeutic effects at doses lower and with a higher safety ratio than the racemic mixture of amisulpride or its salts.

#This invention also relates to a method of treatment utilizing this composition in the therapeutical indications described above.

#The invention is further defined by reference to the following examples describing in detail the preparation of the (S)(−)-amisulpride and salts thereof, the therapeutical potency of (S)(−)-amisulpride in comparison with the racemic mixture and the preparation of a tablet containing the (S)(−)-amisulpride.

#2-methoxy-4-amino-5-ethylthiobenzoic acid

#159 g of 2-methoxy-4-amino-5-mercaptobenzoic acid, 355 cm3 of water and 160 cm3 of 30% sodium hydroxyde solution are placed in a flask fitted with a condenser. The mixture is heated until the solid dissolves, then 123 g of ethylsulfate is added. The mixture is heated to reflux, treated with 10 cm3 of 30% sodium hydroxyde solution, then heated to reflux for 1 hour. After cooling, 800 cm3 of water is added and the solution is filtered. The precipitate obtained by adding 100 cm3 of concentrated hydrochloric acid in the presence of ether is drained, washed with water and dried. 162 g of 2-methoxy-4-amino-5-ethylthio benzoic acid is obtained (yield=88%).