Yttrium-90 and Rhenium-188 Radiopharmaceuticals for Radionuclide Therapy

11.5. YTTRIUM-90 EDTMP
Bone metastases contribute to 25% of all cancer patients and hence it is
essential to develop radiopharmaceuticals for the treatment of bone cancer.
Yttrium-90 EDTMP is a specific bone seeking therapeutic agent, and careful
evaluation of the injected dose into patients is a crucial requirement. Hence, it
is very important to determine chemical purity and RCP of 90 Y EDTMP prior to
injection [11.8].
11.5.1. Methods and results
11.5.1.1. Preparation of 90 Y EDTMP
Yttrium-90 labelled EDTMP was prepared by dissolving 150 mg of EDTMP
in a 25% solution of NH 4 OH, diluted to 10 mL with water and pH adjusted to
~8–8.5. A volume of 1 mL of this solution was labelled with 5 mCi of 90 Y, and
then the pH was again adjusted to 6.5 using 0.1M ammonium chloride. The
reaction was kept at room temperature for 15 min. The RCP was determined
using an LS 6500 Beckman instrument.
(a)
Procedure for purity determination
Take the labelled solution and measure it following the method described by
Volkert et al. [11.9]. Test solution = 100 μL of 90 Y EDTMP + 10 mL (0.1M) HCl.
Take 100 μL from the solution above and transfer it to column exchange Sephadex
C-25 gel chromatography materials after washing with 0.9% NaCl (saline)
(initial activity), which was eluted from the column. Free 90 Y stays in the column
exchange. To remove the free 90 Y, wash the column again with 15–20 mL of
saline (activity in column exchange). The RCP can be determined from:
⎛ activity in column exchange
RCP(%) = −
⎝⎜ 1
⎞
initial activity ⎠⎟ ×100
11.5.1.2. Quality control
Paper chromatography with 90 Y labelled EDTMP was carried out using
Whatman paper 3M as the stationary phase and NH 4 OH:MeOH:H 2 O, in the
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