Production and quality control of 123I-MIBG at IPEN-CNEN/SP

Three iodine radioisotopes are commonly used as a label for MIBG: 123I; 131I and 125I. The superior physical characteristics of the radionuclide have made 123I-MIBG an even more effective diagnostic agent. The cost and physical half-life are limitations, the radioisotope is not easily available for general use and only clinicians within the proximity of a cyclotron facility have access to the radiopharmaceutical. Sodium [123I]-iodide was obtained in Cyclone-30 (IBA) at IPEN-CNEN/SP. The production process uses the following nuclear reaction: 124Xe (p,2n) →123Cs →123Xe→123I. The 124Xe gas is highly enriched (> 99.8 %) which results in ultra pure 123I end product. After irradiation, the 124Xe gas is removed cryogenically. The [123I] activity on the wall target is rinsed with 40 - 50 mL sterile water. The [123I]active solution is transferred to the hot-cell and percolated through a strong anionic resin. The 123I is eluted in 2.5 - 3.0 mL 0.02 N NaOH. The labeling process is based in the cooper (I)-assisted exchange radiodination methods using MIBG-sulphate, (NH4)2SO4 and CuSO4 at 165 - 1700C during 30 minutes and the final active solution sterilized, under aseptic conditions, by 0.22 μm Millipore filter. The final product is kept at low temperature before quality control approval and delivery to Nuclear Medicine Centers. The radiochemical and radionuclide purity of 123I were determined in Whatmann 3MM paper (1.5 x 12cm) in 85% MeOH (Rf *I- = 0.75 and Rf *IO3- = 0.40) and by γ-ray spectroscopy using hiper pure Ge-detector, respectively, before labeling procedure. The microbiological analysis is determined in different culture-medium incubated at room temperature and at 350C ± 2. The apirogenicity is evaluated using the 'in-vitro' Limulus test (LAL). The retention of 123I-solution, in a strong anionic resin, was greater than 99.00 % and the recovery of 123I-Na was more than 97 % of total activity in 3 mL of 0.02 N NaOH. The radiochemical and radionuclide purities of 123I-Na were 99.00 and 98.9 %, respectively. The radiochemical purity was > 98.0 % in all 123I-MIBG routine productions without purification step. The method have been developed, validated and simplified to extend it to a large-scale productions at IPEN-CNEN/SP. The specific activity obtained is suitable for cardiac evaluation and to study the adrenergic receptor system of the heart implicated in several diseases