Clomiphene citrate induces ovulation in anovulatory women by:
- A Directly stimulating FSH and LH secretion from the anterior pituitary
- B Inhibiting granulosa cell aromatase, reducing oestradiol and raising FSH by negative feedback removal
- C Blocking oestrogen receptors in the hypothalamus, removing negative feedback and increasing GnRH pulse frequency ✓
- D Agonising LH receptors on theca cells to increase androgen substrate for follicular development
Correct answer: C. Blocking oestrogen receptors in the hypothalamus, removing negative feedback and increasing GnRH pulse frequency
Explanation
Clomiphene is a selective oestrogen receptor modulator (SERM) that competitively blocks oestrogen receptors in the hypothalamus. By blocking oestrogen's negative feedback, it increases pulsatile GnRH release, which drives increased FSH and LH secretion from the pituitary, stimulating ovarian follicular development and ovulation. Despite partial agonist properties, clomiphene's net hypothalamic effect is anti-oestrogenic, which is the basis of its clinical use in PCOS-related anovulation.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.