How is rituximab (rituximab) administered as an intravenous (IV) infusion?

Rituximab Intravenous Administration

Rituximab is administered as an intravenous infusion at a standard dose of 375 mg/m² body surface area, typically given once weekly for 4 consecutive weeks, though the specific regimen varies by indication. 1

Standard Dosing Regimens by Indication

Lymphoma and Hematologic Malignancies

• For B-cell non-Hodgkin's lymphoma: Administer 375 mg/m² IV once weekly for 4 weeks as the standard monotherapy regimen 1, 2
• For diffuse large B-cell lymphoma in combination with CHOP: Give 375 mg/m² IV on day 1 of each chemotherapy cycle (typically 6-8 cycles), administered 1 day before chemotherapy 1
• For Burkitt lymphoma/leukemia: Eight infusions of rituximab at 375 mg/m² are recommended as the standard when combined with intensive chemotherapy 1
• For CD20-positive B-cell acute lymphoblastic leukemia: Administer eight doses of rituximab 375 mg/m² during induction and consolidation cycles, or 16-18 infusions depending on the protocol 1

Autoimmune Conditions

• For immune thrombocytopenia (ITP): Use 375 mg/m² IV once weekly for 4 consecutive weeks, though lower doses may be sufficient 1
• For inflammatory myopathies: Two 1000 mg doses administered 2 weeks apart (on days 1 and 15), or alternatively 375 mg/m² once weekly for 4 weeks 3, 4
• For Waldenström's macroglobulinemia: Administer 375 mg/m² IV weekly for 4 cycles, often in combination with other agents 1, 3
• For pemphigus vulgaris: Give 1000 mg IV on Day 1 and Day 15, then repeat at Week 24 and Week 26 5
• For granulomatosis with polyangiitis/microscopic polyangiitis (GPA/MPA): Four weekly infusions of 375 mg/m² on days 1,8,15, and 22 during remission induction 5

Alternative Fixed-Dose Regimen

For certain autoimmune conditions, a fixed-dose regimen of 1000 mg IV on day 1 and repeated on day 15 is an acceptable alternative to the body surface area-based dosing. 3, 4 This approach is commonly used for rheumatologic conditions and hypersensitivity pneumonitis.

Administration Technique and Premedication

• Premedication is essential: Administer antipyretic (acetaminophen) and antihistamine (diphenhydramine) before each infusion to reduce infusion reactions 4
• For pemphigus vulgaris protocols: Give IV methylprednisolone 100 mg prior to each rituximab infusion 5
• For pediatric GPA/MPA patients: Administer a minimum of 3 doses of IV methylprednisolone (30 mg/kg/day, not exceeding 1 g/day) prior to the first rituximab infusion 5

Infusion Rate and Monitoring

• Infusion reactions occur in up to 77% of patients during the first infusion, with decreasing frequency in subsequent infusions 4, 2
• For Grade 1/2 reactions: Slow or temporarily stop the infusion and provide symptomatic treatment 4
• For Grade 3/4 reactions: Stop the infusion immediately and provide aggressive symptomatic treatment 4
• Fatal cardiopulmonary reactions occur in approximately 0.04% to 0.07% of patients, most commonly in those with high circulating malignant cell counts, pulmonary infiltrates, or prior cardiovascular disease 6

Critical Pre-Treatment Assessments

Before initiating rituximab therapy, the following must be obtained:

• Baseline immunoglobulin levels (IgG, IgM, IgA) to monitor for hypogammaglobulinemia risk 3, 4
• Hepatitis B and C antibody screening due to risk of viral reactivation 3, 4
• Latent tuberculosis screening prior to administration 3, 4
• Complete blood count with differential at baseline and at 2-4 month intervals during treatment 3, 4

Important Safety Considerations

• Tumor lysis syndrome occurs in approximately 0.04% to 0.05% of patients, typically within 12-24 hours after the first infusion, with higher risk in patients with high circulating malignant cell counts 6
• Avoid rituximab in patients with active hepatitis B infection due to risk of reactivation 3
• Progressive multifocal leukoencephalopathy is a rare but potentially fatal complication; use caution in immunosuppressed patients 3, 4
• Hypogammaglobulinemia risk increases with multiple courses, particularly affecting patients who receive repeated treatments; monitor serum immunoglobulin levels periodically 1

Duration of Treatment Courses

The duration varies significantly by indication:

• Standard lymphoma protocols: 4 weeks for monotherapy 1
• Extended lymphoma protocols: Treatment duration ranged from 1 to 8 weeks in clinical studies, with most patients receiving 4 weeks 1
• Combination with chemotherapy: One dose per chemotherapy cycle over 6-8 cycles 1
• Maintenance therapy for GPA/MPA: 500 mg IV every 6 months for 18 months after achieving remission 5