What is the recommended dosage protocol for MABTHERA (rituximab)?

Rituximab (MabThera) Dosage Protocol

The recommended dosage protocol for MabThera (rituximab) varies by indication, with the standard regimen for non-Hodgkin's lymphoma being 375 mg/m² administered intravenously once weekly for 4 weeks. 1

Dosing Protocols by Indication

Non-Hodgkin's Lymphoma

• Initial dosing: 375 mg/m² IV once weekly for 4 weeks 1
• For indolent NHL: 375 mg/m² IV weekly for 4 doses, either as monotherapy or in combination regimens 1
• For maintenance therapy in high tumor burden patients: 375 mg/m² one dose every 8 weeks for 12 doses 1
• For patients initially treated with single-agent rituximab: 375 mg/m² one dose every 8 weeks for 4 doses as consolidation 1

Rheumatoid Arthritis and Autoimmune Conditions

• Standard dosing: 1000 mg administered on days 1 and 15 2
• Alternative regimen: 375 mg/m² once weekly for 4 weeks 2

ANCA-Associated Vasculitis

• Induction therapy: 375 mg/m²/week × 4 weeks 3
• Maintenance therapy options:
  • 500 mg × 2 at complete remission, and 500 mg at months 6,12, and 18 thereafter (MAINRITSAN scheme) 3
  • 1000 mg infusion after induction of remission, and at months 4,8,12, and 16 after the first infusion (RITAZAREM scheme) 3

Idiopathic Inflammatory Myopathies

• 1000 mg repeated on day 15, or 375 mg/m² once weekly for 4 weeks 2, 3

Pediatric GPA/MPA

• 375 mg/m² BSA, once weekly for four weeks (on days 1,8,15, and 22) 4
• Additional treatment may be given at or after Month 6 to maintain remission 4

Administration Guidelines

Pre-Treatment Assessment

• Obtain baseline immunoglobulin levels (IgG, IgM, IgA) 2
• Screen for hepatitis B and C 2
• Screen for latent tuberculosis 2
• Check IgA levels before administering IVIG (if IVIG is being used in combination therapy) 3

Infusion Protocol

• First infusion: Start at a slower rate and gradually increase if tolerated
• Subsequent infusions: Can be administered at faster rates if initial infusions were well tolerated
• Monitor for infusion-related reactions, particularly during first infusion 2

Safety Considerations

• Severe infectious complications are a concern, particularly in immunosuppressed patients 2
• Progressive multifocal leukoencephalopathy has been reported in patients treated with rituximab 2
• Monitor for viral reactivation, particularly hepatitis B virus 1
• Consider prophylaxis for tumor lysis syndrome in high-risk patients 1

Special Population Considerations

Elderly Patients

• For elderly or infirm patients with indolent NHL who cannot tolerate combination therapy: rituximab 375 mg/m² IV weekly for 4 doses 1
• Age-based dose reductions may be needed in certain conditions (e.g., ANCA-associated vasculitis) 3

Renal Impairment

• Reduce dose by 0.5 mg/kg/day for GFR <30 ml/min/1.73 m² in certain combination regimens 3

Monitoring During Treatment

• Complete blood count with differential at baseline and at 2-4 month intervals 2
• Clinical response assessment through disease-specific parameters 2
• For lymphoma patients, FDG-PET/CT is recommended for post-treatment assessment 2

Common Pitfalls and Caveats

• Infusion-related reactions occur in the majority of patients, usually with the first infusion 5
• IgM flare is a common concern when initiating therapy for Waldenström's macroglobulinemia 2
• Avoid rituximab in patients with active hepatitis B infection due to risk of reactivation 2
• For patients with relapsing disease, reinduction therapy (preferably with rituximab) is recommended 3