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.