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# Arsildx
## Overview
Arsildx is a formulation of arsenic trioxide. It is a cytotoxic agent that induces apoptosis in cancer cells.
## Primary Indications
* Acute Promyelocytic Leukemia (APL) in patients who are refractory to or have relapsed from retinoid and anthracycline chemotherapy.
## Adult Dosing
* **Induction:** 0.15 mg/kg/day intravenously (IV) until complete remission or for up to 60 days.
* **Consolidation:** 0.15 mg/kg/day IV twice weekly for 5 days per week for 4 weeks, or 0.15 mg/kg/day IV once daily for 5 days per week for up to 5 weeks, in two courses. Dosing schedules may vary; consult institutional protocols.
* **Maintenance:** Typically not given with Arsildx; standard practice involves ATRA (all-trans retinoic acid).
## Pediatric Dosing
Dosing in pediatric patients is not well-established and should be determined by a pediatric oncologist based on a risk-stratified approach. Extrapolation from adult data is generally guided by body surface area or weight.
## Dose Adjustments
* **Leukocytosis:** Dose interruption or reduction may be necessary if white blood cell (WBC) count increases significantly. Adjunctive chemotherapy (e.g., ATRA, idarubicin) may be used to manage severe leukocytosis.
* **QTc Prolongation:** Dose interruption or reduction may be required if QTc interval becomes prolonged.
* **Other Toxicities:** Dose adjustments may be needed for severe adverse events.
## Contraindications
* Hypersensitivity to arsenic trioxide or any component of the formulation.
* Pregnancy and breastfeeding.
## Adverse Effects
* **Common:** Leukocytosis, fever, nausea, vomiting, diarrhea, abdominal pain, headache, fatigue, rash, edema, hyperglycemia.
* **Serious:** QTc prolongation (risk of Torsades de Pointes), differentiation syndrome (fever, dyspnea, weight gain, infiltrates on chest X-ray, organ dysfunction), hyperleukocytosis, hepatotoxicity, nephrotoxicity, peripheral neuropathy, cardiac arrhythmias, myelosuppression.
## Key Drug Interactions
* **Drugs prolonging the QTc interval:** Additive risk of QTc prolongation and Torsades de Pointes (e.g., antiarrhythmics, antipsychotics, certain antibiotics).
* **Potassium- and Magnesium-depleting drugs:** Increased risk of QTc prolongation.
* **CYP450 substrates:** Potential for altered metabolism, though clinical significance is often unclear.
## Monitoring
* **Baseline and frequent ECGs:** Monitor QTc interval.
* **Electrolytes:** Potassium, magnesium, calcium.
* **Complete Blood Count (CBC) with differential:** Monitor WBC, platelets, and hemoglobin.
* **Liver Function Tests (LFTs):** Monitor AST, ALT, bilirubin.
* **Renal Function Tests:** Monitor BUN, creatinine.
* **Glucose levels.**
* **Signs and symptoms of differentiation syndrome.**
## Clinical Pearls
* Differentiation syndrome is a potentially life-threatening condition that can occur early in treatment. Prompt recognition and management (e.g., with dexamethasone) are crucial.
* Strict monitoring of the QTc interval is essential due to the risk of fatal arrhythmias. Correct electrolyte abnormalities and consider QTc-prolonging agents cautiously.
* Leukocytosis is common and often managed with adjunctive therapy rather than dose reduction of arsenic trioxide.
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*Disclaimer: This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and institutional guidelines before initiating or modifying therapy.*
