Bromocriptine prolactinomas

Bromocriptine, pergolide Ergot derivatives used in Parkinson s disease (see Chapter 28) and prolactinoma (see Chapter 37) ... 

A 35-year-old woman who had taken lithium carbonate 800 mg/day for 2 years was also given risperidone 6 mg/ day for a manic relapse. She missed two menstrual periods and had galactorrhea. A head CT scan showed a pituitary microadenoma and the prolactin concentration was 125 pig/l (reference range up to 20 pg/1). Risperidone withdrawal resulted in disappearance of the prolactinoma. Her other symptoms persisted and did not change with olanzapine 2.5 mg/day however, bromocriptine 12.5 mg/day for 2 weeks relieved her symptoms and the prolactin concentration normalized. 

Cabergoline appears to be more effective than bromocriptine for the medical management of prolactinomas and offers the advantage of less-frequent dosing and decreased adverse events. 

Bromocriptine was the first D2-receptor agonist to be used in the treatment of hyperprolactinemia and has been the mainstay of therapy for over 20 years. It inhibits the release of prolactin by directly stimulating postsynaptic dopamine receptors in the hypothalamus. Hypothalamic release of dopamine (prolactin-inhibitory hormone) inhibits the release of prolactin. Decreases in serum prolactin concentrations occur within 2 hours of oral administration with maximal suppression occurring after 8 hours, and suppressive effects persisting for up to 24 hours. Medical therapy with bromocriptine normalizes prolactin serum concentrations, restores gonadotropin production, and shrinks tumor size in approximately 90% of patients with prolactinomas. ... 

The hypoglycaemic stress induced in this patient did not cause the expected rise in serum cortisol. It is essential, therefore, that he is commenced on cortisol replacement before surgery. His low T combined with the abnormal response in his TSH (i.e., the 60 min level being greater than the 30 min level) would support a diagnosis of secondary hypothyroidism. He should therefore also be commenced on thyroxine replacement. As prolactinomas frequently shrink dramatically in response to bromocriptine he may be treated with this drug... 

Bromocriptine (PARLODEL) is the dopamine-receptor agonist against which newer agents are compared. Bromocriptine is a semisynthetic ergot alkaloid that interacts with dopamine receptors to inhibit spontaneous and TRH-induced release of prolactin to a lesser extent, it also activates Dj receptors. Bromocriptine normalizes serum prolactin levels in 70-80% of patients with prolactinomas and decreases tumor size in more than 50fo of patients, including those with macroadenomas. 

Patients with prolactinomas who wish to become pregnant comprise a special subset of hyperprolactinemic patients. Because experience with bromocriptine is more extensive than that with any other receptor agonist, bromocriptine is recommended as the first-line treatment in this setting. Bromocriptine relieves the inhibitory effect of prolactin on ovulation and permits most patients with prolactinomas to become pregnant without apparent detrimental effects on pregnancy or fetal development. 

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