Domperidone is a dopamine receptor antagonist that does not readily cross the blood-brain barrier. It demonstrates a potent affinity for the rat D2 receptor with a Ki value of 0.3 nM (IC50 = 13.6 nM) and is also reported to inhibit the rat D3 receptor with an IC50 value of 2.68 nM. Both antiemetic and upper gastrointestinal tract prokinetic activities of domperidone have been evaluated in clinical trials.
