BEXAROTENE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BEXAROTENE (BEXAROTENE).
Selective retinoid X receptor (RXR) agonist; modulates gene expression involved in cell differentiation and apoptosis.
| Metabolism | Primarily hepatic via cytochrome P450 3A4 (CYP3A4) and isoenzymes of the CYP3A subfamily. |
| Excretion | Primarily metabolized in the liver via CYP3A4; metabolites are excreted in feces (approximately 70%) and urine (approximately 10%). Less than 1% of unchanged drug is excreted in urine. |
| Half-life | Terminal elimination half-life is approximately 7 hours in patients with cutaneous T-cell lymphoma; no significant accumulation with repeated dosing. |
| Protein binding | >99% bound to plasma proteins, primarily albumin and lipoproteins. |
| Volume of Distribution | Approximately 4 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: Approximately 90% (well absorbed with high-fat meal). Topical gel: systemic absorption minimal (<1% of applied dose). |
| Onset of Action | Oral: Clinical response may be observed within 4-8 weeks; topical gel: response may be seen within 4-8 weeks, but maximal effect may take longer. |
| Duration of Action | Duration of action is related to dosing interval; sustained exposure required for therapeutic effect. After discontinuation, drug levels decline with half-life of ~7 hours. |
300 mg/m2 orally once daily on days 1 through 28 of a 28-day cycle for cutaneous T-cell lymphoma.
| Dosage form | CAPSULE |
| Renal impairment | No specific dose adjustment recommendations. Use with caution in severe renal impairment (GFR <30 mL/min) due to limited data. |
| Liver impairment | Contraindicated in patients with Child-Pugh class C hepatic impairment. Reduce starting dose to 150 mg/m2 daily in Child-Pugh class B. Monitor liver function closely. |
| Pediatric use | Safety and efficacy not established in pediatric patients; no recommended dosing available. |
| Geriatric use | No specific dose adjustment required, but monitor for adverse effects more frequently due to potential renal and hepatic function decline. Start at low end of dosing range if comorbidities present. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BEXAROTENE (BEXAROTENE).
| Breastfeeding | Contraindicated. No data on M/P ratio; likely excreted in milk due to lipophilicity. Risk of adverse effects in infant, so breastfeeding not recommended. |
| Teratogenic Risk | Pregnancy category X. First trimester: High risk of major congenital malformations (CNS, cardiovascular, craniofacial) and spontaneous abortion. Second and third trimesters: Continued risk of fetal harm; avoid use. Effective contraception required before, during, and after therapy. |
| Fetal Monitoring |
■ FDA Black Box Warning
None (no FDA boxed warning).
| Serious Effects |
["Hypersensitivity to bexarotene or any component of the formulation.","Pregnancy (FDA Pregnancy Category X)."]
| Precautions | ["Hepatic toxicity: Monitor liver function tests before and during therapy; dose reduction or discontinuation if significant elevation.","Hematologic toxicity: May cause leukopenia, anemia, thrombocytopenia; monitor complete blood count.","Hypertriglyceridemia: Common; monitor serum lipids and consider lipid-lowering therapy if necessary.","Pregnancy: Fetal harm may occur; females of reproductive potential must use effective contraception.","Pancreatitis: Associated with elevated triglycerides; monitor for symptoms.","Drug interactions: Avoid concurrent use with CYP3A4 inhibitors or inducers; be cautious with gemfibrozil (increased risk of hepatotoxicity)."] |
| Food/Dietary | Take with food to enhance absorption. Avoid grapefruit and grapefruit juice due to CYP3A4 inhibition. High-fat meals may increase absorption. Limit alcohol intake as it may exacerbate hypertriglyceridemia. |
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| Monitor liver function tests, fasting serum lipids, thyroid function, and CBC. Pregnancy test required before initiation, monthly during therapy, and 1 month after discontinuation. |
| Fertility Effects | May cause reversible menstrual irregularities and ovarian dysfunction. Potential for impaired fertility; no human data on long-term effects. |
| Clinical Pearls | Bexarotene can cause severe hypertriglyceridemia and central hypothyroidism; monitor fasting lipid panel and thyroid function tests at baseline and periodically. Start at a dose of 300 mg/m²/day, and adjust based on triglyceride levels and adverse effects. Due to CYP3A4 metabolism, avoid strong inhibitors/inducers. Use with caution in patients with hepatic impairment. |
| Patient Advice | Take this medication with a meal to improve absorption. · Avoid grapefruit juice and grapefruit products during treatment. · You will need regular blood tests to check your cholesterol, triglycerides, and thyroid function. · Use effective contraception during treatment and for at least one month after stopping, as this drug can cause fetal harm. · Report symptoms of pancreatitis (severe abdominal pain) or hypothyroidism (fatigue, cold intolerance) immediately. |