Table 1.
Differences between 131I-tositumomab and 90Y-ibritumomab tiuxetan
| Property | 131I-tositumomab | 90Y-ibritumomab tiuxetan |
| Antibody | Murine, anti-CD20 | Murine, anti-CD20 |
| Dosing determination | After dosimetry to ensure safe target total body exposure | Fixed dose or per body weight |
| Radiation absorbed in normal tissue | Yes, particularly the thyroid | Yes, particularly marrow and liver |
| Pre-dosing with naked antibody | Yes | Yes |
| Radioisotope – radiation | Iodine-131 emitting γ and β radiation | Ytrium-90 emitting β radiation |
| Target | CD20 receptor on mature B cells | CD20 receptor on mature B cells |
| Radioisotope 1/2 life | 8 days | 2.7 days |