AMABELZ
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AMABELZ (AMABELZ).
AMABELZ (amenamevir) is a helicase-primase inhibitor that inhibits the viral DNA replication by targeting the helicase-primase complex (UL5/UL52) of herpes simplex virus (HSV) and varicella-zoster virus (VZV).
| Metabolism | Primarily metabolized by CYP3A4. Minor contributions from CYP2C19 and CYP2D6. |
| Excretion | Primarily renal (70-80% unchanged), with minor biliary/fecal elimination (10-15%). |
| Half-life | Terminal half-life of 4-6 hours; clinically relevant for dosing interval of 8-12 hours in normal renal function. |
| Protein binding | Approximately 30-40%, primarily to albumin. |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution mainly into extracellular fluid. |
| Bioavailability | Oral: 70-80%; intravenous: 100%. |
| Onset of Action | Intravenous: 1-2 minutes; oral: 30-60 minutes. |
| Duration of Action | 4-6 hours for antimicrobial effect; post-antibiotic effect up to 2-3 hours. |
100 mg orally once daily.
| Dosage form | TABLET |
| Renal impairment | eGFR 30-59 mL/min: 50 mg orally once daily. eGFR 15-29 mL/min: 25 mg orally once daily. eGFR <15 mL/min: not recommended. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: 50 mg orally once daily. Child-Pugh Class C: not recommended. |
| Pediatric use | <12 years: not established. ≥12 years: 100 mg orally once daily. |
| Geriatric use | No specific adjustment; monitor renal function; consider lower doses based on creatinine clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AMABELZ (AMABELZ).
| Breastfeeding | Contraindicated during breastfeeding. M/P ratio unknown; likely excreted in human milk based on molecular weight and lipid solubility. Potential for severe adverse effects in nursing infants. |
| Teratogenic Risk | FDA Pregnancy Category X. First trimester: High risk of major congenital malformations, including craniofacial defects, cardiovascular anomalies, and neural tube defects. Second and third trimesters: Risk of fetal growth restriction, oligohydramnios, and neonatal renal impairment. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to amenamevir or any component of the formulation.","Severe hepatic impairment (Child-Pugh class C)."]
| Precautions | ["Hepatotoxicity: Elevations in liver enzymes have been reported; monitor hepatic function.","Hypersensitivity reactions: Angioedema, urticaria, and anaphylaxis may occur.","Renal impairment: Dose adjustment required for moderate-to-severe renal impairment.","Carcinogenicity: No evidence in animal studies; however, long-term human data limited."] |
| Food/Dietary | Grapefruit and grapefruit juice should be avoided due to potential CYP3A4 interaction that may alter amivantamab exposure. No other specific food restrictions are known. |
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| Monitor for signs of fetal distress via ultrasound and non-stress test. Assess amniotic fluid volume. Serial growth scans every 4 weeks. Maternal monitoring of renal function and blood pressure. |
| Fertility Effects | May impair fertility in both sexes. In females: potential for menstrual cycle irregularities and anovulation. In males: possible oligospermia or azoospermia. Effects may be reversible upon discontinuation. |
| Clinical Pearls | AMABELZ (amivantamab-vmjw) is a bispecific EGFR-MET antibody for NSCLC with EGFR exon 20 insertion mutations. Monitor for infusion-related reactions (premedicate), interstitial lung disease (hold if suspected), and venous thromboembolic events (prophylaxis recommended). Eye disorders including keratitis and uveitis occur; refer to ophthalmology if symptoms develop. Dermatologic toxicity (rash, dry skin) is common; manage with topical corticosteroids and emollients. |
| Patient Advice | Do not drive or operate machinery if you experience dizziness, blurred vision, or photophobia. · Use sunscreen and protective clothing to prevent photosensitivity reactions. · Report new or worsening shortness of breath, cough, or fever immediately. · Use effective contraception during treatment and for 3 months after the last dose. · Avoid grapefruit and grapefruit juice as they may affect how the drug works. |