[Antiemetic effect of the levo isomer of sulpiride (L-sulpiride) in humans].

Vomiting represents one of the most dangerous complications of general anesthesia. L-sulpiride has been able to control this complication very effectively. We studied the effect on vomiting of two doses of L-sulpiride (50/100 mg). Both these doses have been effective in reducing the episodes of vomiting other than in preventing nausea and retching if considered versus controls and also versus droperidol at the doses of 5 mg (50 mg L-sul = 12%, 100 mg = 4%, droperidol = 20%, controls = 28%). L-sulpiride is an antagonist of dopamine on D2 receptors therefore inhibits the action of dopamine increasing the secretion of prolactin. During the surgical distress per se prolactin levels are increased. Together with the increment of catecholamines, high concentration of prolactin can evoke arrhythmias. In view of this possibility we studied the time course of the administration of the two doses of L-sulpiride and of droperidol on prolactin secretion. Both of the drugs increased the plasma levels of prolactin. Droperidol-induced increase in prolactin secretion was significant already at ten minutes after the administration reaching the peak after 20 minutes. L-sulpiride increased prolactin secretion reaching the maximum increase 20 minutes after the administration of 50 mg of the drug, and 30 minutes after the administration of 100 mg doses. The hyperprolactinemizing action of droperidol lasts for at least 8 hours, whereas L-sulpiride action lasts 4 hours.