[A simple and rapid routine preparation of no-carrier added meta-I-123- and I-131-iodobenzylguanidine (I-123-MIBG and I-131-MIBG) for clinical nuclear medicine applications].

AIM: Low specific activity meta-iodobenzylguanidine (I-123/I-131-MIBG) is currently used in the assessment of abnormalities in the myocardial neuroadrenergic function as well as in the management of neuroendocrine tumors. In recent studies an enhanced cardiac and tumor uptake were reported by the use of high specific activity radiopharmazeuticals, suggesting a potential clinical benefit of no-carrier-added (n.c.a.) I-123/I-131-MIBG. In this paper we describe a simple and improved preparation of I-123-MIBG and I-131-MIBG for routine clinical application, feasible in any nuclear medicine department.

METHODS: N.c.a I-123-MIBG and n.c.a. I-131-MIBG were prepared by Cu(I)-assisted [I-123/I-131]iodo-debromination at 170-175 degrees C with 86 +/- 6% and 80 +/- 10% radiochemical yield respectively and high specific activity (> or = 4.3 TBq/mumol and > or = 0.21 TBq/mumol), starting from meta-bromobenzylguanidine (MBBG). The total time of synthesis including the HPLC purification and the preparation of the injectable solution was less than 60 min.

RESULTS: Neither rechromatography by HPLC nor TLC gave any indication of disintegration products in the injection solution up to 8 h after preparation. Moreover, biological testings confirmed that the buffered and sterile-filtered n.c.a. I-123-MIBG and n.c.a. I-131-MIBG solutions are isotonic, sterile and apyrogenic and thus suitable as injectable solutions for clinical use.

CONCLUSION: High specific activity I-123-MIBG and I-131-MIBG could now be prepared by a simple one-step reaction giving rise to high radiochemical yields and high purity for a widespread clinical applications. Therefore, this encourages clinical validations on a large scale to answer the question of whether n.c.a. I-123-MIBG and I-131-MIBG could play an important role in the assessment of the myocardial sympathetic nervous dysfunction as well as in the diagnosis and therapy of neuroendocrine tumors.