Which medications are the most likely cause of this patient’s symptoms and laboratory findings? A 32-year-old woman with a history of schizophrenia presents to the physician with amenorrhea and a milky discharge from both nipples. A pregnancy test is negative. Laboratory results show an increased level of prolactin, decreased gonadotropin levels, and normal thyroid function tests.

Chlorpromazine

The correct answer is D. Chlorpromazine is an antipsychotic used in the treatment of schizophrenia and psychosis. Chlorpromazine blocks dopamine D2 receptors and thus blocks the effects of excess dopamine associated with schizophrenia. Because dopamine inhibits the secretion of prolactin, a dopamine antagonist such as chlorpromazine can cause hyperprolactinemia by decreasing the inhibitory effects of dopamine Answer A is incorrect. Amantadine is used for influenza A prophylaxis, and because it causes release of dopamine from intact nerve terminals, it is also used in the treatment of Parkinsons disease Answer B is incorrect. Bromocriptine is a dopamine agonist that decreases, rather than increases, prolactin levels and is actually used for the treatment of hyperprolactinemia Answer C is incorrect. Cabergoline, like bromocriptine, is a dopamine agonist that decreases prolactin levels Answer E is incorrect. One of the atypical antipsychotics, clozapine blocks 5-HT2 and dopamine receptors. It tends to have fewer extrapyramidal adverse effects than drugs such as chlorpromazine, including hyperprolactinemia. However, one of the more worrisome adverse effects of clozapine is agranulocytosis.