About Sulpiride Synthetic Origin, D2 Antagonist. Mechanism of Action of Sulpiride Sulpride block both dopamine D1 and D2 receptors, Sulpiride is more selective and acts primarily as a dopamine D2 antagonist. Sulpiride appears to lack effects on norepinephrine, acetylcholine, serotonin, histamine, or gamma-aminobutyric acid (GABA) receptors. Indications for Sulpiride Schizophrenia Interactions for Sulpiride 1.Concurrent use with lithium increases the risk of extrapyramidal side effects 2.Concurrent use with antacids or sucralfate may affect sulpiride absorption 3.Efficacy may be reduced by dopamine agonists 4.Increased postural hypotension if used with other antihypertensive drugs