Plasma prolactin levels after acute and subchronic oral administration of domperidone and of metoclopramide: a cross-over study in healthy volunteers.

Domperidone is a new potent anti-emetic drug which, in contrast with metoclopramide, does not cross the blood brain barrier. The aim of the present study was to find out whether peripheral dopaminergic blockage by domperidone causes prolactin release, and if so, whether this prolactin release persists during longer-term treatment. For comparison, metoclopramide, which blocks both peripheral and central dopamine receptors, was studied using a cross-over trial design. After acute oral administration of both drugs, prolactin levels increased 10-fold. After further treatment with metoclopramide the prolactin levels were further increased to 15-fold, but after prolonged administration of domperidone a decrease to a plasma level 6-fold higher than basal was observed. The clincial implications of these findings are discussed.