Administration
In order to qualify for ibritumomab, a patient needs to have bone marrow involvement of < 25% and > 15% bone marrow cellularity. Since ibritumomab is known to cause cytopenia, platelet and neutrophil counts are also taken pretreatment. Refractory/relapsed patients should have platelet counts of 100,000 per cubic millimetre (100,000/cmm) or greater; consolidation patients should have counts of 150,000/cmm or greater. Since a murine antibody is used, the patient might also be tested for human anti mouse antibodies (HAMA). Having bulky disease does not disqualify a patient.
The ibritumomab regimen takes 7–9 days. An imaging dose of the drug is no longer required in the U.S. Rituxan 250 mg/sq.m is given day 1, then on day 7-9 the Rituxan dose is repeated and Zevalin given within four hours. The dose of Zevalin 0.4 mCi/kg (= 14.8MBq/kg) if platelet counts are above 150,000/cmm; 0.3 mCi/kg (= 11.1MBq/kg) if 100,000-150,000/cmm. The Zevalin dose never exceeds 32 mCi (= 1184MBq).
Ibritumomab tiuxetan is administered by intravenous infusion which usually lasts around 10 minutes. Only acrylic shielding is needed, not lead.
Read more about this topic: Ibritumomab Tiuxetan