CLOMIPHENE CITRATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Selective estrogen receptor modulator; competes with estrogen for binding at estrogen receptors in the hypothalamus, inhibiting negative feedback and increasing gonadotropin-releasing hormone (GnRH) secretion, leading to increased LH and FSH release from the pituitary.
| Metabolism | Hepatic metabolism; excreted in feces; active metabolites (possibly enterohepatic recirculation). |
| Excretion | Primarily fecal (approximately 50%), with about 8% renal excretion of unchanged drug and metabolites. Biliary excretion is significant, with enterohepatic recirculation contributing to prolonged elimination. |
| Half-life | Terminal elimination half-life is approximately 5–7 days (120–168 hours) for the active zu-isomer, with a longer half-life for its metabolites. This prolonged half-life leads to accumulation with repeated dosing and sustained clinical effects. |
| Protein binding | Approximately 80–90% bound to albumin, with significant binding to other plasma proteins including sex hormone-binding globulin (SHBG). |
| Volume of Distribution | Apparent volume of distribution is large, approximately 50–100 L/kg, indicating extensive tissue distribution and accumulation, particularly in the liver and reproductive organs. |
| Bioavailability | Oral: ~100% absorbed, but bioavailability is difficult to quantify due to extensive first-pass metabolism and enterohepatic cycling; essentially complete systemic exposure after oral administration. |
| Onset of Action | Oral: 5–10 days for therapeutic effect on ovulation induction; peak effect on gonadotropin release occurs within 5–10 days of a 5-day course. |
| Duration of Action | Duration of effect on ovulation lasts approximately 5–10 days after a 5-day course, but antiestrogenic effects (e.g., on cervical mucus) may persist for up to 2–3 weeks. The drug can be detected in plasma for up to 6 weeks due to its long half-life. |
50 mg orally once daily for 5 days, starting on day 5 of menstrual cycle; may increase to 100 mg orally once daily for 5 days if ovulation not achieved.
| Dosage form | TABLET |
| Renal impairment | No specific dose adjustment guidelines; use with caution in severe renal impairment (CrCl <30 mL/min) due to limited data. |
| Liver impairment | Contraindicated in patients with liver disease or hepatic dysfunction; no Child-Pugh based adjustments available. |
| Pediatric use | Not recommended for use in children; safety and efficacy not established. |
| Geriatric use | Not indicated for use in elderly patients; no specific dosing recommendations. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions May cause visual disturbances and ovarian hyperstimulation syndrome.
| Breastfeeding | Excreted into breast milk; M/P ratio unknown. Clomiphene may reduce milk production due to anti-estrogenic effects. Because of potential for adverse reactions in nursing infants, women are advised not to breastfeed during treatment. |
| Teratogenic Risk | FDA Pregnancy Category X. Clomiphene citrate is contraindicated in pregnancy. First trimester exposure associated with neural tube defects, cleft palate, and syndactyly. Second and third trimester: no data due to contraindication. Risk of multiple gestation (5-12%) increases risks of preterm labor, low birth weight, and congenital anomalies. |
■ FDA Black Box Warning
Should not be used in patients with liver disease or abnormal uterine bleeding of undetermined origin.
| Common Effects | Ovarian enlargement |
| Serious Effects |
Pregnancy; liver disease or history; abnormal uterine bleeding of undetermined origin; ovarian cyst or enlargement due to polycystic ovary syndrome; hypersensitivity to clomiphene.
| Precautions | Ovarian enlargement/cysts; visual disturbances; multiple pregnancy; ovarian hyperstimulation syndrome; vasomotor symptoms; blurred vision; prolonged use may increase risk of borderline or invasive ovarian tumors. |
| Food/Dietary | No significant food interactions. Avoid excessive alcohol consumption as it may impair fertility. |
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| Fetal Monitoring | Monitor ovarian response with ultrasound and serum estradiol to detect ovarian hyperstimulation syndrome (OHSS). Perform pregnancy test before each cycle if menses not followed. In pregnancy, monitor for multiple gestation and ectopic pregnancy. Assess for signs of OHSS (rapid weight gain, abdominal pain, oliguria). |
| Fertility Effects | Induces ovulation in anovulatory women by blocking estrogen receptors at hypothalamus, increasing gonadotropin release. May cause luteal phase defects. Overuse may deplete ovarian follicles. No proven negative effect on oocyte quality when used appropriately. |
| Clinical Pearls | Monitor ovarian size and estradiol levels to reduce risk of ovarian hyperstimulation syndrome (OHSS). Use only in patients with ovulatory dysfunction; rule out pregnancy before each cycle. Limit to 6 treatment cycles due to increased risk of ovarian cancer with prolonged use. |
| Patient Advice | Take clomiphene citrate exactly as prescribed, typically for 5 days starting on day 3-5 of menstrual cycle. · Ovulation usually occurs 5-10 days after the last dose; have intercourse every other day during this window. · Common side effects include hot flashes, mood swings, and visual disturbances; report persistent visual changes immediately. · Risk of multiple pregnancy (mainly twins) is increased; discuss with healthcare provider. · Avoid use if pregnant, have liver disease, or have abnormal vaginal bleeding. |