A 32-year-old woman with bipolar disorder on valproate develops polycystic ovarian morphology, irregular menses, hyperandrogenism, and weight gain. Which pharmacological property of valproate most likely explains these endocrine effects?
- A Sodium channel blockade reducing LH pulsatility
- B Direct antagonism of FSH receptors in the ovary
- C Induction of CYP3A4 reducing estrogen levels
- D Inhibition of HDAC (histone deacetylase) altering hypothalamic-pituitary gene expression ✓
Explanation
Valproate inhibits histone deacetylase (HDAC), which alters epigenetic regulation of gene expression in the hypothalamic-pituitary-gonadal axis. This epigenetic mechanism is thought to contribute to its association with polycystic ovarian-like syndrome (PCOS) in women, including hyperandrogenism, anovulation, and polycystic ovaries. Valproate is not a sodium channel blocker primarily (it has multiple mechanisms including GABA enhancement and T-type calcium channel modulation). It does not directly block FSH receptors. Valproate is actually a CYP enzyme inhibitor (not inducer), so it raises levels of co-administered drugs.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.