••• Chapter 59^ Disorders of Prolactin Secretion^593
❍ Which dopamine agonists are available for treatment of hyperprolactinemia?
Cabergoline—used once or twice weekly, probably more effective and less nauseating than bromocriptine, effective
in patients resistant to bromocriptine as well.
Bromocriptine—often used twice a day. It has been on the market for more then 20 years, which makes it a safe
choice for pregnant patients
Pergolide—no longer recommended as it has been shown to cause valvular heart disease
Quinoglide, bromocriptine depo—are still being studied
❍ True or False: Does cabergoline have a higher frequency of pituitary tumor shrinkage compared with other
dopamine agonists?
True. It is hypothesized that cabergoline has a higher affinity for the dopamine receptor binding sites.
❍ When can one expect prolactin level to fall after initiation of dopamine agonist therapy?
Usually it happens within 2 to 3 weeks.
❍ Dopamine agonists restore ovulation in what percentage of cases?
90%.
❍ What percentage has cessation of galactorrhea after bromocriptine therapy?
50% to 60% have cessation; 75% have reduction in galactorrhea. Thus, cessation of galactorrhea is slower and may
not occur as frequently as resumption of ovulation/menses.
❍ When can one expect decrease in size of adenoma after initiation of dopamine agonist therapy?
It is always preceded by fall in prolactin levels. One may see tumor shrinking after 6 weeks, though usually it is
observed within 6 months.
❍ When can one expect improvement in visual symptoms after initiation of dopamine agonist therapy?
Patient should be reassessed within 1 month, although improvement may occur within a 24 to 72 hours.
❍ What are the side effects of therapy with dopamine agonists?
Most common is nausea. Others include postural hypotension, headache, dizziness, constipation, and fatigue. Less
common are vomiting, nasal congestion, depression, and Raynaud phenomenon. Rare cardiovascular events.
❍ How can side effects of dopamine agonists be minimized?
Start with half dose, take it with food, give medication at bedtime, and then add second dose in the morning after
the patient is tolerating the night dose. In women, nausea can be avoided by vaginal administration.
❍ What is the regimen for bromocriptine therapy?
Start at 1.25 mg after dinner or at bedtime for 1 week, then increase to 1.25 mg twice a day. After 1 month,
evaluate for side effects and prolactin levels. May increase the dose up to 5 mg bid. The dose that results in normal
serum prolactin level should be continued.