Bromocriptine is a dopamine agonist which suppresses prolactin secretion in healthy people and in patients with prolactin secreting tumours. It increases growth hormone secretion in some normal subjects but paradoxically lowers growth hormone secretion in up to 70% of patients with acromegaly.
Reports on the efficacy of bromocriptine therapy in acromegaly vary widely. Growth hormone levels are reduced in the majority of patients but are rarely completely suppressed. Greater remission of the soft tissue features of acromegaly may occur in some patients than would be expected from changes in growth hormone levels as determined by immunoassay.
The major advantage of bromocriptine therapy in acromegaly is its lack of effect on pituitary function, other than growth hormone and prolactin secretion, and avoidance of the complications of surgical or radiation treatment. Its major disadvantages are that the majority of patients only show a partial response, and the degree of compliance required with long term therapy. It is a useful adjunct to surgical and radiation treatment. In the few large studies of bromocriptine treatment used alone the results obtained over a limited period compare favourably with those obtained by radiotherapy.