Yttrium-90 and Rhenium-188 Radiopharmaceuticals for Radionuclide Therapy

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The generator was prepared, investigated and validated for different
parameters such as yield, breakthrough and its utility for the preparation of
radiopharmaceutical products.
The design comprised three columns connected in series (length 21 cm,
diameter 4 mm and 1 g of Sr-Spec in each column). The first column was
used for absorbing 90 Sr, whereas the second and third columns were used as
safety columns for further purification.
A stock solution of 90 Sr in 3M nitric acid was passed through the columns,
whereby 90 Sr was retained in the column and 90 Y was eluted. Subsequently,
90 Sr was stripped from the column with dilute 0.05M nitric acid.
AG 50 resin was used for further purification to remove any traces of
organic materials and trace elements [11.2, 11.3].
11.3.1.1. Purification of 90 Y eluate
This procedure was designed to remove as many impurities, such as
ZrO 2+ , Fe 3+ , Cu 2+ and Zn 2+ , as possible, which could be present, along with 90 Y,
during the production process. Briefly, the 90 Y solution was passed through a
9 cm long × 0.4 cm wide column containing AG 50WX-12 resin in H + form
followed by 15 mL of 0.5M H 2 SO 4 to remove ZrO 2+ . Subsequently, 40 mL of
2M HNO 3 was used to remove 90 Sr followed by 25 mL of 2M HCl to eliminate
Fe 3+ , Cu 2+ , Zn 2+ and other impurities. Finally, 12 mL of 4M HCl solution was
passed through the column to elute purified 90 Y. The acid was removed by
heating, and the 90 Y was dissolved in a small volume of 0.01M HCl solution
[11.4]. Figure 11.2 illustrates the elution pattern of 90 Y through the three columns.
11.3.1.2. Stability of columns
To determine the reproducibility of the generator, experiments were carried
out wherein the generator system was loaded with different quantities (25, 50,
100, 150 or 200 mCi) of 90 Sr, and the system was eluted every day with 20 mL of
3M nitric acid. The system was stable for up to one week (four elution processes
after which 90 Sr breakthrough increased by a magnitude of ten). The resin column
could be reused six to seven times if washed with 20 mL of 2% oxalic acid,
20 mL of water and finally with 20 mL of 0.01M EDTA.
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