Semiautomated labelling and fractionation of yttrium-90 and lutetium-177 somatostatin analogues using disposable syringes and vials.

OBJECTIVES

The treatment of tumours expressing somatostatin receptors with yttrium-90 (90Y)-labelled and lutetium-177 (177Lu)-labelled somatostatin analogues is one of the most interesting therapeutic approaches adopted in nuclear medicine in recent years. However, the process of synthesis and fractionation of these radiopharmaceuticals is still mainly carried out manually despite the high radiation exposure to the operators and the need to comply with good manufacturing practices. In this study a semiautomatic synthesizer [automatic dose dispenser (ADD-2)] using only disposable syringes and vials has been presented.

MATERIALS AND

METHODS

Small-scale syntheses (185-555 MBq) of 90Y/177Lu-DOTATATE were performed by adding the appropriate amount of peptide to a 90Y/177Lu chloride solution (n=10). The radionuclide/peptide molar ratio was 1 : 17 and 1 : 2 for 90Y and 177Lu, respectively. The solutions were buffered to 4.6 pH by ascorbate buffer and heated at 90°C for 30 min. Radiochemical purity was assessed by two independent radio-thin-layer chromatography systems. The solutions were fractioned to mimic the preparation of patient doses.

RESULTS

All synthesis and fractionation steps were performed using ADD-2. The radiochemical yield was 92 ± 3% for 90Y and 97 ± 1% for 177Lu labelling. Radiochemical purity was more than 99.5%. The accuracy and reproducibility of the instrument in transferring and fractionating radioactive solutions were high (maximal error ≈ 5%).

CONCLUSION

ADD-2 appears suitable for use in clinical preparations of 90Y/177Lu-DOTATATE with therapeutic amounts of precursors (20-30 GBq). The operator's exposure to radiation by using ADD-2 in comparison with manual preparations is under investigation.