Rituximab is a chimeric monoclonal antibody that targets the CD20 antigen expressed on the surface of pre-B and mature B lymphocytes. It is a cornerstone of therapy for various B-cell malignancies and autoimmune disorders. In the Indian context, it is a critical, high-cost therapy often requiring careful patient selection, financial planning, and stringent infusion monitoring due to the high risk of infusion-related reactions.
Adult: NHL: 375 mg/m² body surface area (BSA) intravenously once weekly for 4 or 8 doses. CLL: 375 mg/m² BSA in cycle 1, then 500 mg/m² BSA in subsequent cycles (up to 6 cycles) in combination with chemotherapy. RA, GPA, MPA: Two 1000 mg intravenous infusions separated by 2 weeks. Subsequent courses based on clinical evaluation, typically every 6-12 months.
Note: MUST be administered as an intravenous infusion. NEVER as an intravenous push or bolus. First infusion: Start at 50 mg/hr. If no infusion reaction, increase by 50 mg/hr increments every 30 minutes to a maximum of 400 mg/hr. Subsequent infusions: Start at 100 mg/hr, increase by 100 mg/hr increments every 30 minutes to a maximum of 400 mg/hr. Dilute in 0.9% Sodium Chloride or 5% Dextrose to a final concentration of 1-4 mg/mL. Administer with mandatory premedication.
Rituximab binds specifically to the CD20 antigen, a transmembrane phosphoprotein expressed on the surface of normal pre-B and mature B lymphocytes, and on >90% of B-cell non-Hodgkin lymphomas (NHL). The CD20 antigen is not shed from the cell surface and does not internalize upon antibody binding. The Fab domain of Rituximab binds to the CD20 antigen on B lymphocytes, and the Fc domain recruits immune effector functions to mediate B-cell lysis.
Pregnancy: Pregnancy Category C. Human IgG antibodies cross the placental barrier. Rituximab may cause B-cell depletion in the fetus. Use only if potential benefit justifies potential risk to the fetus. Women of childbearing potential should use effective contraception during and for up to 12 months after treatment.
Driving: Patients may experience dizziness, fatigue, or visual disturbances during or after infusion. They should be cautioned not to drive or operate machinery until they know how the medication affects them.
| Cisplatin | Increased risk of nephrotoxicity; monitor renal function closely. | Major |
| Live Vaccines (e.g., MMR, Varicella, Yellow Fever) | Risk of disseminated infection due to immunosuppression. Avoid vaccination during and after treatment (consult guidelines for timing). | Major |
| Antihypertensives | Infusion reactions can cause hypotension; may potentiate antihypertensive effect. Monitor BP closely during infusion. | Moderate |
| Other Immunosuppressants (e.g., Cyclophosphamide, high-dose Corticosteroids, TNF inhibitors) | Additive immunosuppression, significantly increasing risk of serious infections. | Major |
Same composition (Rituximab (500mg)), different brands: