A 23-year-old woman presents for evaluation of a 7-month history of amenorrhea. Examination discloses bilateral galactorrhea and normal breast and pelvic examinations. Pregnancy test is negative. Which of the following classes of medication is a possible cause of her condition?

Amenorrhea and galactorrhea may be seen when something causes an increase in prolactin secretion or action. The differential diagnosis involves several possible causes. Excessive estrogens, such as with birth control pills, can reduce prolactin- inhibiting factor, thus raising serum prolactin level. Similarly, intensive suckling (during lactation and associated with sexual foreplay) can activate the reflex arc that results in hyperprolactinemia. Many antipsychotic medications, especially the phenothiazines, are also known to have mammotropic properties. Hypothyroidism appears to cause galactorrhea secondary to thyrotropin-releasing hormone (TRH) stimulation of prolactin release. When prolactin levels are persistently elevated without obvious cause (e.g., in breast-feeding), evaluation for pituitary adenoma becomes necessary.