Toremifene

FDA label

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Renal PK of toremifene and N-demethyltoremifene similar in renal impairment; no specific adjustment stated

Hepatic Elimination half-life increased <2-fold in hepatic impairment (cirrhosis/fibrosis); exercise caution; no specific adjustment stated

Instructions

• Correct hypokalemia/hypomagnesemia before initiating; monitor electrolytes periodically
• Baseline ECG and as clinically indicated in patients at increased risk
• Periodic CBC, calcium levels, and LFTs; baseline and annual gynecologic examinations

Available strengths

• tab 60 mg

Contraindications

• Congenital or acquired QT prolongation (long QT syndrome)
• Uncorrected hypokalemia or uncorrected hypomagnesemia

Cautions

• QT prolongation/torsade de pointes — avoid QT-prolonging drugs and strong CYP3A4 inhibitors; caution in CHF, hepatic impairment, electrolyte abnormalities
• Hepatotoxicity — Grade 3/4 transaminitis, hyperbilirubinemia, jaundice, hepatitis, NAFLD reported; periodic LFTs
• Hypercalcemia and tumor flare in bone metastases during first weeks — discontinue if hypercalcemia severe
• Uterine malignancy risk — endometrial cancer, hyperplasia, polyps reported; monitor high-risk patients
• History of thromboembolic disease — generally do not treat
• Rare leukopenia/thrombocytopenia — monitor counts in affected patients

Adverse reactions

• Most common: hot flashes (35%), sweating (20%), nausea (14%), vaginal discharge (13%), dizziness, edema, vomiting, vaginal bleeding
• Serious (≥1%): thromboembolic events (pulmonary embolism, thrombophlebitis), MI, ischemic attack

Pregnancy Category D — can cause fetal harm (embryo-fetal toxicity below human dose in animals); premenopausal women must use effective non-hormonal contraception

Lactation Unknown if present in human milk (excreted in rat milk) — discontinue nursing or the drug