Zevalin(ibritumomab tiuxetan)isthe immunoconjugate resulting from a stable thiourea covalent bond between the monoclonal antibody ibritumomab and the linker-chelator tiuxetan [N-[2-bis(carboxymethyl)amino]-3- (p-isothiocyanatophenyl)-propyl]-[N-[2-bis(carboxymethyl)amino]-2- (methyl)-ethyl]glycine. This linker-chelator provides a high affinity, conformationally restricted chelation site for Indium-111 or Yttrium-90. The approximate molecular weight of ibritumomab tiuxetan is 148 kD. The antibody moiety of Zevalin is ibritumomab, a murine IgG₁ kappa monoclonal antibody directed against the CD20 antigen.

Ibritumomab tiuxetan is a clear, colorless, sterile, pyrogen-free, preservative-free solution that may contain translucent particles. Each single-use vial includes 3.2 mg of ibritumomab tiuxetan in 2mL of 0.9% Sodium Chloride.

Physical/Radiochemical Characteristics of In-111

Indium-111 decays by electron capture, with a physical half-life of 67.3 hours (2.81 days). The product of radioactive decay is non-radioactive Cadmium-111. Radiation emission data for In-111 are summarized in Table 4.

Table 4. Principal In-111 Radiation Emission Data

External Radiation

The exposure rate constant for 1 mCi (37 MBq) of In-111 is 8.3 x 10^-4 C/kg/hr (3.2 R/hr) at 1 cm.

To allow correction for physical decay of In-111, the fractions that remain at selected intervals before and after the time of calibration are shown in Table 5.

Table 5. Physical Decay Chart: In-111 Half-life 2.81 Days (67.3 Hours)

Physical/Radiochemical Characteristics of Y-90

Yttrium-90 decays by emission of beta particles, with a physical half-life of 64.1 hours (2.67 days). The product of radioactive decay is non-radioactive Zirconium-90. The range of beta particles in soft tissue(χ₉₀) is 5 mm. Radiation emission data for Y-90 are summarized in Table 6.

Table 6. Principal Y-90 Radiation Emission Data

External Radiation

The exposure rate for 1 mCi (37 MBq) of Y-90 is 8.3 x 10^-3 C/kg/hr (32 R/hr) at the mouth< of an open Y-90 vial.

To allow correction for physical decay of Y-90, the fractions that remain at selected intervals before and after the time of calibration are shown in Table 7.

Table 7. Physical Decay Chart: Y-90 Half-life 2.67 Days (64.1 Hours)

Bookmark this page: