Neukine (filgrastim)

# Neukine (filgrastim) ## Overview Filgrastim is a recombinant human granulocyte colony-stimulating factor (G-CSF). It stimulates the production, maturation, and differentiation of neutrophils from bone marrow stem cells. ## Primary Indications * Reduction of the duration of neutropenia and the incidence of febrile neutropenia in patients with non-myeloid malignancies receiving myelosuppressive anti-cancer chemotherapy. * Reduction of the duration of neutropenia in patients with cancer undergoing bone marrow transplantation (BMT) or peripheral blood progenitor cell transplantation (PBPCT) expected to result in clinically significant neutropenia. * Mobilization of peripheral blood progenitor cells (PBPCs) for autologous PBPCT. * Severe chronic neutropenia (congenital, cyclic, or idiopathic) in patients with a neutrophil count of ≤ 1.5 x 10^9/L and a history of severe or recurrent infections. ## Adult Dosing **Chemotherapy-induced neutropenia:** * **Dose:** 5 mcg/kg/day. * **Frequency:** Subcutaneous injection once daily. * **Initiation:** Typically initiated at least 24 hours after the last dose of chemotherapy. * **Duration:** Continue daily until the absolute neutrophil count (ANC) has reached at least 2 x 10^9/L, or until the ANC has returned to the expected nadir and then remained consistently above 1.5 x 10^9/L for 3 consecutive days. * **Maximum Dose:** Generally not to exceed 10 mcg/kg/day. Some protocols may allow higher doses (e.g., up to 20 mcg/kg/day) based on clinical response, but this is less common. **Bone marrow transplantation (BMT) / Peripheral blood progenitor cell transplantation (PBPCT):** * **Dose:** 10 mcg/kg/day. * **Frequency:** Subcutaneous injection once daily. * **Initiation:** Typically initiated at least 24 hours after chemotherapy, or 24 hours after infusion of bone marrow or PBPCs. * **Duration:** Continue daily until the ANC has reached at least 2 x 10^9/L, or until the ANC has returned to the expected nadir and then remained consistently above 1.5 x 10^9/L for 3 consecutive days. * **Maximum Dose:** Generally not to exceed 10 mcg/kg/day, though higher doses may be used in specific BMT protocols under strict supervision. **Mobilization of peripheral blood progenitor cells (PBPCs):** * **For autologous transplantation:** * **Dose:** 10 mcg/kg/day. * **Frequency:** Subcutaneous injection once daily. * **Duration:** Continue daily for up to 14 days. Apheresis is typically initiated when the patient's PBPC yield is sufficient, usually when the circulating ANC is ≥ 2 x 10^9/L. * **Post-apheresis:** May be continued for up to 7 days after the last apheresis if needed. * **Maximum Dose:** 10 mcg/kg/day for mobilization. **Severe chronic neutropenia:** * **Dose:** Initially 5 mcg/kg/day. * **Frequency:** Subcutaneous injection once daily. * **Titration:** Dose may be increased in increments of 5 mcg/kg/day every 1-2 weeks to maintain an ANC between 1.5 x 10^9/L and 2 x 10^9/L. * **Maximum Dose:** Generally not to exceed 10 mcg/kg/day. ## Pediatric Dosing Pediatric dosing is often weight-based and may vary based on the indication and institutional protocol. **Chemotherapy-induced neutropenia:** * **Dose:** 5 mcg/kg/day, administered subcutaneously. * **Initiation and Duration:** Similar to adults, initiated 24 hours after chemotherapy and continued until ANC recovery. * **Maximum Dose:** Generally up to 10 mcg/kg/day. **Bone marrow transplantation (BMT) / Peripheral blood progenitor cell transplantation (PBPCT):** * **Dose:** 10 mcg/kg/day, administered subcutaneously. * **Initiation and Duration:** Similar to adults. * **Maximum Dose:** Generally up to 10 mcg/kg/day. **Severe chronic neutropenia:** * **Dose:** Typically 1.2 mcg/kg/day (0.0012 mg/kg/day), administered subcutaneously. * **Titration:** Dose may be increased in increments of 1.2 mcg/kg/day every 1-2 weeks to maintain ANC between 1.5 x 10^9/L and 2 x 10^9/L. * **Maximum Dose:** May be increased up to 12 mcg/kg/day (0.012 mg/kg/day) in some cases. **Note:** Specific pediatric dosing can be highly protocol-dependent, especially in oncology settings. Always refer to institutional guidelines. ## Dose Adjustments Dose adjustments are generally not required for renal or hepatic impairment, but caution and closer monitoring may be warranted. Doses are often escalated or de-escalated based on ANC response, particularly in chronic neutropenia. ## Contraindications * Hypersensitivity to filgrastim, E. coli-derived proteins, or any component of the formulation. * Myeloid tumors: Filgrastim is generally not indicated for patients with myeloid malignancies as it can potentially stimulate tumor growth. ## Adverse Effects * **Common:** Bone pain, musculoskeletal pain, headache, fever, rash, diarrhea, nausea, vomiting, alopecia. * **Serious:** Splenomegaly (especially with long-term use in chronic neutropenia), acute respiratory distress syndrome (ARDS), sickle cell crisis, allergic reactions (including anaphylaxis), capillary leak syndrome, vasculitis, thrombocytopenia. ## Key Drug Interactions * **Chemotherapeutic agents:** Filgrastim should generally not be administered within 24 hours before or after cytotoxic chemotherapy, as it may enhance the myelosuppressive effects. * **Lithium:** May potentiate the effect of filgrastim by increasing neutrophil counts; monitor closely. ## Monitoring * **Complete Blood Count (CBC) with differential:** Monitor ANC frequently, especially during chemotherapy and BMT/PBPCT. Typically daily monitoring is needed initially, then every other day, and then twice weekly as ANC normalizes. * **Platelet count:** Monitor, as thrombocytopenia can occur. * **Liver function tests (LFTs) and Renal function tests (RFTs):** Monitor periodically. * **Spleen size:** Assess clinically, particularly in patients with chronic neutropenia, due to the risk of splenomegaly. ## Clinical Pearls * Filgrastim is administered via subcutaneous injection. Intravenous administration is generally reserved for specific situations (e.g., some mobilization protocols) or when subcutaneous administration is not feasible, and doses may differ. * Filgrastim should not be shaken vigorously due to potential denaturation. * In chronic neutropenia, the goal is to maintain an ANC between 1.5 x 10^9/L and 2 x 10^9/L to prevent infections, not to normalize the neutrophil count. * Educate patients on subcutaneous injection technique and proper storage. * The risk of splenomegaly and splenic rupture is a serious concern with prolonged use, especially in chronic neutropenia. Patients should be monitored for left upper quadrant pain or shoulder pain. *** **Disclaimer:** This information is intended for clinical pharmacists and healthcare professionals. It is essential to consult the most current prescribing information, relevant clinical guidelines, and institutional protocols for complete and up-to-date details before administering any medication. Dosing and management can vary significantly based on individual patient factors and specific clinical scenarios.