Effect of the amisulpride isomers on rat prolactinemia

The effects on rat serum prolactin level of the two isomers constituting the racemic form of amisulpride were compared. (S-)-amisulpride induced hyperprolactinemia at lower doses (ED50=0.09±0.01 mg/kg) than racemic- (ED50=0.24±0.03 mg/kg) and (R+)-amisulpride (ED50=4.13±0.05 mg/kg), in accord with their affinities for pituitary dopamine D2 receptor (Ki=3.8±0.2, 6.4±0.2 and 143.3±2.3 nM, respectively). At doses twice the ED50, (S-)-amisulpride produced a maximal increase in prolactin level similar to that of the racemic form (403±21% and 425±15%, respectively), but higher than that of (R+)-amisulpride (198±8%). These results suggest that the hyperprolactinemia induced by the racemic-amisulpride is mostly due to its (S-)-isomer. © 2002 Elsevier Science B.V. All rights reserved.