RADIOCHEMICAL PURITY OF I-131-LABELED METAIODOBENZYLGUANIDINE INFUSION FLUIDS - A REPORT FROM CLINICAL-PRACTICE

Iodine-131 labelled metaiodobenzylguanidine ([I-131]MIBG) has a diagno stic and therapeutic role in the management of neural crest tumours, p articularly neuroblastoma, malignant phaeochromocytoma and paraganglio ma. With therapeutic amounts of [I-131]MIBG it is essential that the a mount of free [I-131]iodide, the most important impurity, is known. In clinical practice the percentage of free [I-131]iodide seen in a [I-1 31]MIBG infusion concentrate increased from 2.2% +/- 0.67% to 3.6% +/- 0.39% (mean +/- SD; n = 23) 1 day after production. At the time of us e the percentage of free [I-131]iodide was always below our upper limi t of acceptance of 5%. Since 5% of free [I-131]iodide is within practi cal reach in our environment, a higher percentage at the time of pread ministration quality control is not accepted in the Netherlands Cancer Institute.