Bromocriptine has a similar mode of action to dopamine in stimulating dopamine receptors on the prolactin-secreting pituitary cells. Stimulation of these receptors leads to inhibition of both prolactin secretion and synthesis. After a single 2.5 mg dose of bromocriptine administered at 0900 to women with hyperprolactinaemia, prolactin secretion was inhibited within two hours and reached nadir at seven hours. When patients are treated chronically using 2.5mg three times per day, prolactin levels are maintained within the normal range, that is, less than 20ng/ml (400mu/l), throughout a twenty-four-hour period (Fig. 4.12).
