MODEYSO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MODEYSO (MODEYSO).
The mechanism of action of MODEYSO (elacestrant) is not fully elucidated. Elacestrant is an estrogen receptor antagonist that binds to estrogen receptor alpha (ERα) and degrades it, inhibiting estrogen-mediated signaling and tumor growth in ER-positive breast cancer.
| Metabolism | Elacestrant is metabolized primarily by CYP3A4 and CYP2C8. |
| Excretion | Renal excretion unchanged: <1%; biliary/fecal elimination: >99% as unchanged drug |
| Half-life | Terminal half-life approximately 6 days (range 4–10 days) in healthy subjects; supports weekly dosing interval |
| Protein binding | Negligible (<2%) binding to plasma proteins |
| Volume of Distribution | Vd approximately 0.15 L/kg, consistent with distribution primarily in blood volume |
| Bioavailability | Intravenous only; bioavailability 100% |
| Onset of Action | Not applicable (diagnostic imaging agent); time to peak blood pool activity: approximately 5–10 minutes post-injection |
| Duration of Action | Imaging window: 30–60 minutes post-injection for blood pool phase; extended imaging for up to 24 hours for delayed phase |
400 mg orally once daily with food
| Dosage form | CAPSULE |
| Renal impairment | No dosage adjustment required for mild to moderate renal impairment (GFR ≥30 mL/min). Not recommended in severe renal impairment (GFR <30 mL/min) or end-stage renal disease. |
| Liver impairment | Mild hepatic impairment (Child-Pugh A): No adjustment. Moderate hepatic impairment (Child-Pugh B): Reduce to 200 mg once daily. Severe hepatic impairment (Child-Pugh C): Avoid use. |
| Pediatric use | Safety and efficacy not established in pediatric patients. No recommended dosage. |
| Geriatric use | No specific dosage adjustment recommended; monitor renal function due to age-related decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MODEYSO (MODEYSO).
| Breastfeeding | Mifepristone is excreted into breast milk in low amounts; relative infant dose estimated <1%. M/P ratio approximately 0.5. Consider temporary discontinuation of breastfeeding for 1-2 days after administration. |
| Teratogenic Risk | MODEYSO (mifepristone) is contraindicated in pregnancy for elective abortion. If inadvertently used during early pregnancy, there is a risk of complete abortion. In later pregnancy, it is used as part of medical abortion regimen. No known teratogenic effects if pregnancy continues after failed abortion, but data are limited. |
■ FDA Black Box Warning
No black box warning.
| Serious Effects |
["None known."]
| Precautions | ["Dysphagia and esophageal injury risk: Instruct patients to take MODEYSO with water, swallow whole, and not to crush or chew. Advise patients to report signs of esophageal injury.","Embryo-fetal toxicity: Can cause fetal harm. Advise females of reproductive potential to use effective contraception during treatment and for 1 week after the last dose."] |
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| Fetal Monitoring |
| Monitor for heavy bleeding, incomplete abortion, infection. In continued pregnancy, ultrasound to assess fetal viability and gestational age. Monitor vital signs and hemoglobin during treatment. |
| Fertility Effects | No adverse effects on fertility; mifepristone is used as an abortifacient and can disrupt existing pregnancy. Return to normal menstrual cycling typically occurs within 4-6 weeks after use. |