A comparative review of the tolerability profiles of dopamine agonists in the treatment of hyperprolactinaemia and inhibition of lactation.

Dopamine agonists are the treatment of choice for the majority of patients with hyperprolactinaemic disorders. Although characterised by a relatively high incidence of adverse effects, most commonly gastrointestinal, cardiovascular and neurological, these are usually mild and transient, and can be minimised by starting with a low dose and gradually increasing it, or taking the drug with food or while recumbent. Bromocriptine, introduced in 1971, is the reference preparation against which newer dopamine agonists are compared. It is effective in suppressing prolactin secretion, reducing prolactinoma size and restoring gonadal function. However, up to 12% of patients cannot tolerate the drug at therapeutic dosages. Cabergoline, a long-acting dopamine agonist administered once or twice weekly, has been shown to be significantly more effective than bromocriptine in suppressing prolactin secretion in hyperprolactinaemic patients, and is better tolerated, particularly in terms of nausea and vomiting. In suppressing physiological lactation, cabergoline is at least as effective as bromocriptine, and is associated with significantly fewer rebound symptoms and adverse effects. Quinagolide is a non-ergot dopamine agonist that is administered once daily. It has similar efficacy to bromocriptine, but is probably less effective than cabergoline in hyperprolactinaemic patients; it is not licensed for suppression of lactation. It is better tolerated than twice-daily bromocriptine, but is probably inferior to cabergoline in this regard. Neither bromocriptine, cabergoline nor quinagolide has been associated with any detrimental effect on pregnancy or fetal development. However, experience with bromocriptine is far more extensive; thus, for women requiring treatment for subfertility, this drug remains the treatment of choice in most centres, with cabergoline and quinagolide as acceptable second-line drugs in bromocriptine-intolerant patients. In hyperprolactinaemic men, hyperprolactinaemic women not wishing to become pregnant, and for suppression of physiological lactation, cabergoline is recommended as first-line treatment.