TRUXIMA
Clinical safety rating: caution
Truxima (rituximab-abbs) is a biosimilar CD20-directed cytolytic antibody used in the treatment of non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis, and microscopic polyangiitis. It is a key component of chemoimmunotherapy regimens and biologic therapy for autoimmune conditions, offering a targeted B-cell depletion approach.
TRUXIMA (rituximab-abbs) is a chimeric murine/human monoclonal IgG1 kappa antibody that binds specifically to the CD20 antigen on B-lymphocytes. It mediates B-cell lysis via complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC).
| Metabolism | Rituximab-abbs is a monoclonal antibody not metabolized by cytochrome P450 enzymes; elimination occurs via intracellular catabolism and target-mediated clearance. |
| Excretion | Primarily eliminated via reticuloendothelial system and target-mediated clearance. Renal excretion is minimal (<1% unchanged in urine) due to large molecular weight. Biliary/fecal excretion accounts for <5%. |
| Half-life | Mean terminal elimination half-life is approximately 21 days (range 14.4–38.7 days) in clinical studies for rheumatoid arthritis. Longer half-life observed in patients with lower tumor burden. Clinical context: supports weight-based dosing every 6 months. |
| Protein binding | Approximately 85–95% bound to plasma proteins, primarily alpha-2-macroglobulin and complement components. |
| Volume of Distribution | Vd approximately 0.1–0.15 L/kg for rituximab (TRUXIMA is a rituximab biosimilar). Clinical meaning: limited to vascular and interstitial spaces, negligible distribution into tissues. |
| Bioavailability | Subcutaneous: approximately 90% relative to intravenous (based on area under curve). Intravenous: 100%. |
| Onset of Action | Subcutaneous: Clinical effect (improvement in signs/symptoms) observed within 4–8 weeks after first dose. Intravenous: Similar onset, within 4–8 weeks. |
| Duration of Action | Duration of effect persists for approximately 6 months after a single dose, corresponding to sustained serum concentrations above therapeutic threshold. Clinical notes: retreatment recommended at 6-month intervals based on disease activity. |
| Molecular Weight | 144100 |
{"non-Hodgkin’s_lymphoma":"375 mg/m² IV weekly for 4 or 8 doses, depending on regimen. May be combined with chemotherapy; premedicate with acetaminophen and an antihistamine.","chronic_lymphocytic_leukemia":"Day 0 of first cycle: 375 mg/m² IV. Cycles 2–6: 500 mg/m² IV on day 1, in combination with fludarabine and cyclophosphamide. Repeat every 28 days.","rheumatoid_arthritis":"Two 1000 mg IV infusions separated by 2 weeks, in combination with methotrexate. Subsequent courses may be given every 16–24 weeks based on clinical response; premedicate with methylprednisolone 100 mg IV or equivalent glucocorticoid.","granulomatosis_with_polyangiitis_and_microscopic_polyangiitis":"375 mg/m² IV weekly for 4 weeks, in combination with glucocorticoids. Premedicate with methylprednisolone and an antihistamine."}
| Dosage form | INJECTABLE |
| Renal impairment | No dosage adjustment is required in patients with renal impairment. Rituximab is not cleared renally. |
| Liver impairment | No formal pharmacokinetic studies have been conducted in patients with hepatic impairment. No dosage adjustment is recommended. |
| Pediatric use | Safety and effectiveness have not been established in pediatric patients. Not currently indicated for use in children. |
| Geriatric use |
| 1st trimester | Rituximab (TRUXIMA) is a humanized monoclonal antibody (IgG1) that crosses the placenta, especially after the first trimester. Use in T1 is generally avoided unless benefit outweighs risk; limited data suggest no major teratogenicity, but B-cell depletion in the fetus may occur. |
| 2nd trimester | Crosses placenta more readily; fetal B-cell depletion, potential for lymphopenia and impaired immune response. Use only if clearly needed, with careful monitoring. |
| 3rd trimester | Crosses placenta actively; may cause neonatal B-cell depletion and immunosuppression. Infants may have prolonged lymphopenia and reduced vaccine response. Avoid if possible; administer only if essential for maternal condition. |
Clinical note
Rituximab may cause fetal B-cell lymphocytopenia. Limited human data are available; in animal studies, rituximab crossed the placenta and caused B-cell depletion in offspring. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.
| Placental transfer | Rituximab is an IgG1 monoclonal antibody; active placental transfer occurs via FcRn receptors, especially after the first trimester. Fetal concentrations can be similar to maternal levels by the third trimester. |
■ FDA Black Box Warning
Fatal infusion reactions, severe mucocutaneous reactions, progressive multifocal leukoencephalopathy (PML), and hepatitis B reactivation with fulminant hepatitis have been reported. Patients should be monitored closely during therapy.
| Common Effects | Infusion-related reactions (fever, chills, rigors, urticaria, pruritus, bronchospasm, hypotension), Fatigue, Nausea, Headache, Upper respiratory tract infection, Neutropenia, Thrombocytopenia, Anemia, Rash, Diarrhea, Peripheral edema, Cough |
| Serious Effects | Fatal infusion reactions, Severe cytopenias (Grade 3–4 neutropenia, thrombocytopenia, anemia), Tumor lysis syndrome, Fulminant hepatitis B reactivation, Progressive multifocal leukoencephalopathy (PML), Severe infections (sepsis, pneumonia, meningitis, hepatitis), Cardiac arrhythmias and heart failure, Severe mucocutaneous reactions (Stevens-Johnson syndrome/toxic epidermal necrolysis), Acute renal failure |
Hypersensitivity to rituximab or any of its excipientsActive severe infections (e.g., hepatitis B, tuberculosis)
| Precautions | Infusion reactions (may be severe or fatal), tumor lysis syndrome (in patients with high tumor burden), serious infections (including bacterial, fungal, and viral), cardiac arrhythmias and angina, bowel obstruction/perforation, renal toxicity in patients with autoimmune diseases, and immunogenicity leading to hypersensitivity reactions. |
Loading safety data…
| No dose adjustment based on age alone is necessary. However, geriatric patients may be at increased risk for infections and cardiac adverse events; monitor closely. |
| Breastfeeding | Rituximab is excreted in human milk at low levels, but the oral bioavailability is poor. The effects on the nursing infant are unknown, but due to the potential for immunosuppression and B-cell depletion, caution is recommended. Consider alternatives or discontinue breastfeeding during therapy and for at least 6 months after the last dose. |
| Lactation Rating | L4 (Limited Data - Potentially Concern) |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: IgG antibodies cross placenta; limited human data suggests no increased risk of major malformations. Second and third trimesters: Potential for fetal B-cell depletion and cytopenias; risk of infection in neonates. Avoid use unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal complete blood counts with differential and lymphocyte subsets prior to and during therapy. For pregnancy, assess fetal growth via ultrasound; evaluate neonate for B-cell count, infections, and vaccination response for 6 months after last dose. |
| Fertility Effects | Animal studies show no impairment of fertility. In humans, no adequate data on fertility effects; rituximab may cause prolonged B-cell depletion and impact reproductive planning. |
| Food/Dietary | No known food interactions. May take with or without food. |
| Clinical Pearls | Monitor for infusion reactions during and after administration; premedicate with antihistamines and corticosteroids. Use sterile technique; do not shake vial. Administer via dedicated IV line with 0.9% NaCl. Consider hepatitis B screening before initiation. |
| Patient Advice | Report any signs of infection, such as fever or cough, immediately. · Avoid live vaccines during treatment and for at least 6 months after. · This drug can cause reactivation of hepatitis B; notify doctor if you have had hepatitis. · You may experience infusion reactions; these are managed by slowing or stopping the infusion. · Do not breastfeed while on this medication and for 6 months after last dose. |