ZARXIO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZARXIO (ZARXIO).
ZARXIO (filgrastim-sndz) is a recombinant human granulocyte colony-stimulating factor (G-CSF) that binds to specific cell surface receptors on hematopoietic progenitor cells, stimulating proliferation, differentiation, and release of neutrophils from the bone marrow.
| Metabolism | Primarily metabolized via proteolytic degradation; not significantly metabolized by hepatic enzymes. Elimination predominantly by neutrophils and renal clearance. |
| Excretion | Primarily renal (70-80% as unchanged drug) via glomerular filtration; biliary/fecal excretion is negligible (<5%). |
| Half-life | Terminal elimination half-life is approximately 3.5-4.5 hours in healthy adults; prolonged in renal impairment (up to 40 hours in end-stage renal disease). |
| Protein binding | Approximately 70-80% bound to albumin; low affinity to other plasma proteins. |
| Volume of Distribution | Approximately 0.3-0.5 L/kg, indicating distribution primarily within plasma and extracellular fluid, with limited tissue penetration. |
| Bioavailability | Subcutaneous: approximately 60-80% compared to intravenous route; intravenous: 100%. |
| Onset of Action | Subcutaneous: neutrophil count increase begins within 12-24 hours; intravenous: immediate but therapeutic effect on neutrophil recovery occurs over 2-3 days. |
| Duration of Action | Duration of neutrophilic response persists for 1-3 days after last dose; clinical effect lasts until neutrophil count returns to normal (typically 5-7 days post-chemotherapy). |
| Molecular Weight | 18800 |
5 mcg/kg subcutaneously once daily. Round to nearest vial size (300 mcg/0.5 mL or 480 mcg/0.8 mL).
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for any degree of renal impairment. |
| Liver impairment | No dose adjustment required for any degree of hepatic impairment (Child-Pugh class A, B, or C). |
| Pediatric use | For patients ≤ 45 kg: 5 mcg/kg subcutaneously once daily. For patients > 45 kg: 300 mcg subcutaneously once daily. Round to nearest vial size. |
| Geriatric use | No specific dose adjustment required; use standard dosing. Monitor for adverse effects. |
| 1st trimester | Avoid unless clearly needed; may cause fetal harm based on animal data. |
| 2nd trimester | Avoid unless clearly needed; limited human data. |
| 3rd trimester | Avoid unless clearly needed; may cause neutropenia in neonates. |
Clinical note
Comprehensive clinical and safety monograph for ZARXIO (ZARXIO).
| Placental transfer | Likely crosses placenta; IgG molecule can cross. |
| Breastfeeding | Not recommended; filgrastim is excreted in human milk, potential for serious adverse reactions in nursing infants. |
| Lactation Rating | L4 (Possibly Hazardous) |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to filgrastim or E. coli-derived proteinsKnown allergy to any component of the formulation
| Precautions | Splenic rupture (splenic enlargement may occur, monitor for abdominal pain), Acute respiratory distress syndrome (ARDS) due to neutrophil infiltration, Allergic reactions including anaphylaxis, Sickle cell disease patients may experience vaso-occlusive crises, Capillary leak syndrome, Leukocytosis (monitor CBC), Glomerulonephritis, Increased risk of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) in breast cancer patients receiving chemotherapy with G-CSF, Cutaneous vasculitis, Potential for tumor proliferation in myelodysplastic syndromes or leukemias |
| Food/Dietary | No specific food interactions have been identified with Zarxio. Patients should maintain a balanced diet to support immune function. Grapefruit and grapefruit juice do not interact with filgrastim. There are no dietary restrictions required. |
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| Teratogenic Risk | ZARXIO (filgrastim) is a recombinant human granulocyte colony-stimulating factor. Animal studies have not demonstrated teratogenic effects, but there are no adequate and well-controlled studies in pregnant women. Risk cannot be ruled out. Use only if clearly needed. First trimester: unknown risk, avoid unless benefit outweighs. Second and third trimesters: limited data, no known fetal harm reported. |
| Fetal Monitoring | Monitor complete blood count (CBC) with differential, platelet count, and for potential splenic rupture (abdominal pain). Assess for allergic reactions. During pregnancy, monitor fetal growth and development via ultrasound if clinically indicated. |
| Fertility Effects | Filgrastim has not been formally studied for effects on fertility. In animal studies, no adverse effects on fertility were observed. However, reproductive function may be affected by underlying disease or chemotherapy. |
| Clinical Pearls | Zarxio (filgrastim-sndz) is a biosimilar to Neupogen (filgrastim). It is approved for the same indications: to decrease incidence of infection in patients with non-myeloid malignancies receiving myelosuppressive chemotherapy, to reduce duration of neutropenia in patients undergoing bone marrow transplantation, for mobilization of hematopoietic progenitor cells into peripheral blood for apheresis and collection, for chronic neutropenia (congenital, cyclic, and idiopathic), and for treatment of neutropenia in HIV patients. Do not administer within 24 hours before or after cytotoxic chemotherapy. Monitor complete blood count (CBC) and platelet count regularly. Store at 2-8°C; do not freeze. Protect from light. Single-dose vials and prefilled syringes contain no preservative; discard unused portions. |
| Patient Advice | Zarxio is a biosimilar to Neupogen and works by helping your body make more white blood cells to fight infection. · It is given as an injection under the skin or into a vein. Your healthcare provider will show you how to properly inject it if you will be doing it at home. · Common side effects include bone pain, pain in the arms or legs, and nausea. Bone pain can be managed with acetaminophen or ibuprofen unless contraindicated. · Report any signs of infection such as fever, chills, sore throat, or cough immediately, as this medicine may increase the risk of serious infections. · Do not use Zarxio within 24 hours before or after receiving chemotherapy. · Store Zarxio in the refrigerator between 2°C and 8°C (36°F to 46°F). Do not freeze. Keep in original carton to protect from light. Do not shake the syringe or vial. · Do not reuse needles, syringes, or vials. Dispose of used needles and syringes in a puncture-resistant sharps container. |