STILPHOSTROL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for STILPHOSTROL (STILPHOSTROL).
Synthetic nonsteroidal estrogen; binds to estrogen receptors, inducing tumor regression in hormone-sensitive cancers.
| Metabolism | Hepatic metabolism via glucuronidation and sulfation; excreted in urine and bile. |
| Excretion | Renal (primarily as glucuronide conjugates, 70-80%); fecal (biliary excretion of conjugates, 20-30%); <5% unchanged |
| Half-life | Terminal elimination half-life: 50-60 hours (range 40-80 hr) due to enterohepatic recirculation; clinical context: steady-state achieved in ~10-14 days |
| Protein binding | ~97% bound, primarily to sex hormone-binding globulin (SHBG) and albumin |
| Volume of Distribution | 1.5-3.0 L/kg; indicates extensive tissue distribution with accumulation in adipose tissue |
| Bioavailability | Oral: 40-50% (first-pass hepatic glucuronidation); Intravenous: 100% |
| Onset of Action | Oral: 4-7 days for clinical response (palliative effect in prostate cancer); Intravenous: 1-3 hours for estrogenic effects; Intramuscular: 24-48 hours |
| Duration of Action | Oral: 2-4 weeks after discontinuation due to slow elimination; Intravenous/Intramuscular: up to 3 weeks; clinical note: prolonged effects due to fat storage and enterohepatic recycling |
0.5-1 mg/kg intravenously daily for 5 days, then 0.5 mg/kg intramuscularly weekly.
| Dosage form | TABLET |
| Renal impairment | No specific adjustment required; caution in severe renal impairment (GFR <30 mL/min) due to limited data. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: not recommended. |
| Pediatric use | Not established; safety and efficacy not determined for patients under 18 years. |
| Geriatric use | Start at lower end of dosing range (0.5 mg/kg) and monitor for increased sensitivity to estrogenic effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for STILPHOSTROL (STILPHOSTROL).
| Breastfeeding | Diethylstilbestrol is excreted into breast milk. The M/P ratio is unknown. Due to potential serious adverse effects in the nursing infant, including endocrine disruption, breastfeeding is not recommended during therapy. |
| Teratogenic Risk | Diethylstilbestrol (STILPHOSTROL) is a known teratogen. First trimester exposure is associated with a high risk of vaginal adenosis, clear cell adenocarcinoma, and cervical structural anomalies in female offspring. Second and third trimester exposure may increase risk of preterm labor and adverse fetal outcomes. Use is contraindicated during pregnancy. |
■ FDA Black Box Warning
None (no FDA boxed warning). However, use in pregnancy is contraindicated due to risk of fetal harm.
| Serious Effects |
["Known hypersensitivity to diethylstilbestrol or any component.","Pregnancy (teratogen).","History of thromboembolic disorders (e.g., DVT, PE).","Undiagnosed abnormal genital bleeding.","Estrogen-dependent neoplasia (e.g., breast cancer, except when used for treatment).","Active hepatic disease or impaired liver function."]
| Precautions | ["Increased risk of thromboembolic events (stroke, pulmonary embolism, DVT).","Fluid retention exacerbating heart failure or hypertension.","Hypercalcemia in patients with bone metastases.","Hepatotoxicity; monitor liver function.","Exacerbation of endometriosis or uterine fibroids.","Impaired glucose tolerance; monitor diabetic patients."] |
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| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes, renal function, and signs of thromboembolism. Fetal monitoring includes ultrasound for growth and anatomy if inadvertent exposure occurs; amniocentesis for karyotype if structural anomalies suspected. |
| Fertility Effects | Diethylstilbestrol may reduce fertility by disrupting ovulation and menstrual cycle. In females, it can cause anovulation and endometrial atrophy. In males, it may suppress spermatogenesis and induce gynecomastia. Effects may be reversible upon discontinuation. |