Clomiphene citrate is a non-steroidal, orally active, selective estrogen receptor modulator (SERM) primarily used for the induction of ovulation in anovulatory women. It acts as a competitive antagonist at estrogen receptors in the hypothalamus, blocking negative feedback and increasing gonadotropin-releasing hormone (GnRH) secretion, thereby stimulating follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release from the pituitary. In the Indian context, it is a first-line, cost-effective treatment for ovulatory dysfunction, particularly in women with Polycystic Ovary Syndrome (PCOS).
Adult: Female: 50 mg (1/2 tablet of 100mg) orally once daily for 5 days, starting on day 3, 4, or 5 of the menstrual cycle (spontaneous or induced). Dose may be increased to 100 mg daily for 5 days in subsequent cycles if ovulation does not occur. Maximum recommended dose is 150 mg/day for 5 days. Therapy beyond 6 cycles is not recommended.
Note: Take with or without food, preferably at the same time each day. The tablet can be split (scored) to achieve a 50mg dose. Treatment should be monitored with ultrasound follicular tracking and/or mid-luteal phase serum progesterone to confirm ovulation. Timed intercourse is usually advised 5-10 days after the last dose.
Clomiphene is a racemic mixture of two isomers (enclomiphene and zuclomiphene) that act as competitive antagonists at estrogen receptor (ER) sites, particularly in the hypothalamus. By blocking the negative feedback of endogenous estradiol on the hypothalamus, it increases the pulsatile secretion of gonadotropin-releasing hormone (GnRH). This, in turn, stimulates the anterior pituitary to secrete increased amounts of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), promoting follicular recruitment, growth, and eventual ovulation.
Pregnancy: Pregnancy Category X. Absolutely contraindicated. Clomiphene has a long half-life; a pregnancy test must be performed before each treatment cycle. There is a theoretical risk of teratogenicity, though studies are inconclusive. Increased risk of multiple gestation.
Driving: Use with caution. May cause dizziness, visual disturbances, or lightheadedness, which could impair the ability to drive or operate machinery.
| Danazol | May inhibit ovulation induced by clomiphene. | Moderate |
| GnRH Agonists (e.g., Leuprolide) | Concurrent use is not standard; may interfere with hormonal axis. | Major |
| Tamoxifen | Additive anti-estrogenic effects; not recommended concurrently. | Moderate |
| Thyroid hormones | Dosage of thyroid hormone may need adjustment as fertility improves. | Moderate |
| CYP2D6 Inhibitors (e.g., Fluoxetine, Paroxetine) | May alter metabolism of clomiphene, potentially increasing levels of parent drug. | Moderate |