A 19-year-old woman with schizophrenia treated with risperidone develops secondary amenorrhea and galactorrhea. Serum prolactin is markedly elevated. Among second-generation antipsychotics, risperidone carries the highest risk of this effect because it:

• A Stimulates dopamine release from the hypothalamus
• B Blocks tuberoinfundibular dopamine receptors at relatively low doses ✓
• C Acts as a potent agonist at pituitary D2 receptors
• D Inhibits hypothalamic dopamine synthesis

Explanation

Tuberoinfundibular dopaminergic neurons tonically inhibit prolactin secretion from the anterior pituitary. Risperidone produces strong D2 blockade at comparatively low doses, disinhibiting prolactin release and causing hyperprolactinemia, amenorrhea, galactorrhea and infertility. Antipsychotics are D2 antagonists, not agonists, and none stimulates hypothalamic dopamine release; amisulpride shares this high prolactin liability while aripiprazole can lower prolactin.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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