Rituximab Dosing for Hypersensitivity Pneumonitis

Dosing Regimens

The American College of Physicians recommends a fixed dose regimen of 1000 mg IV on day 1 and repeated on day 15 for patients with hypersensitivity pneumonitis requiring rituximab therapy 1, 2
The American College of Physicians also recommends a BSA-based regimen of 375 mg/m² IV once weekly for 4 weeks for patients with hypersensitivity pneumonitis requiring rituximab therapy 1, 3
For maintenance therapy in refractory cases, rituximab may be repeated as needed based on clinical response, typically every 24 weeks, as suggested by the American College of Rheumatology 4

Before initiating rituximab therapy, baseline immunoglobulin levels, hepatitis B and C antibody screening, and latent tuberculosis screening should be obtained, as recommended by the American College of Rheumatology 4
The American College of Rheumatology also recommends monitoring complete blood count with differential at baseline and at 2-4 month intervals during treatment 4
Latent tuberculosis screening is also recommended by the Mayo Clinic 1, 4

Premedication with antipyretic and antihistamine is recommended to reduce infusion reactions, as suggested by the European Society for Medical Oncology 5
Infusion reactions occur in up to 77% of patients during the first infusion, and monitoring is crucial, as recommended by the European Society for Medical Oncology 5
For Grade 1/2 reactions, slowing or temporarily stopping the infusion and providing symptomatic treatment is recommended, while for Grade 3/4 reactions, stopping the infusion and providing aggressive symptomatic treatment is suggested by the European Society for Medical Oncology 5

Cytopenias are a common adverse effect of rituximab therapy, as reported by the Mayo Clinic 3
The American College of Physicians and the European Society for Medical Oncology recommend monitoring for increased risk of infections 1, 5
Serious adverse events to monitor include progressive multifocal leukoencephalopathy, hepatitis B reactivation, and severe infections, as recommended by the American College of Physicians and the American College of Rheumatology 1, 2, 4