Yttrium-90 and Rhenium-188 Radiopharmaceuticals for Radionuclide Therapy

of 90 Y complexed to DTPA (R f = 1) was carried out using a high performance
storage phosphor screen (Cyclone, Packard BioScience).
7.2.6. Microbiological tests
For every batch, an aliquot of the product was stored for decay. After
complete decay (>3 months), the sample was tested for sterility and pyrogens.
Sterility was assayed by plating the sample over Petri dishes with growth
medium, and the samples were incubated in a thermostatic oven at 35°C for 14 d.
After incubation, samples were analysed for any growth and, in case of positive
results, the number of colony forming units was determined.
For pyrogens, a control limulus amebocyte lysate (LAL) test based on the
kinetic chromogenic method was used. The LAL test was performed using an
Endosafe-PTS spectrophotometer (Charles River Laboratories International Inc.).
Four samples of volume 25 µL were put in a disposable capillary cassette
containing LAL reagent and an internal standard. The cassette was incubated in
the PTS system and the time of colour formation measured. Time was internally
correlated to the endotoxin amount and the final amount was displayed on the
system. The reference value for parenterals was considered to be 17.5 EU/mL
(EU = endotoxin units).
7.2.7. IART protocol
After tumour resection, the surgeon injected directly into the tumour bed,
100 mg of avidin diluted in 20–30 mL of saline. At a mean of 18 ± 3 h after
avidin administration, 20 mg of biotinylated HSA (chase) was administered
intravenously over 5 min to mop up any circulating avidin before administration
of the radiolabelled biotin. Ten minutes later, 3.7 GBq of 90 Y r-BHD (specific
activity of 4 GBq/mg) was delivered intravenously over 30 min using a dedicated
disposable system.
7.3. RESULTS
7.3.1. Effect of pH on radiolabelling
The synthesis of r-BHD was performed according to the procedure described
by Sabatino et al. [7.10]. The purity of the isolated compound was checked by
reverse phase (RP) HPLC and carbon, hydrogen and nitrogen (CHN) elemental
analysis. The experiments, aimed at evaluating the effect of pH on RCP values,
were performed with a sodium acetate buffer up to pH5.6. The results in Fig. 7.2
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