Carrier-free 131I-meta-iodobenzylguanidine: comparison of production from meta-diazobenzylguanidine and from meta-trimethylsilylbenzylguanidine

Nucl Med Commun. 1994 Apr;15(4):268-74. doi: 10.1097/00006231-199404000-00157.


Meta-iodobenzylguanidine (MIBG) is a drug which is selectively accumulated by the uptake-1 process in adrenergic tissues. When labelled with 131I, it may be used for the targetted radiotherapy of tumours such as phaeochromocytoma and neuroblastoma. This paper describes the preparation of carrier-free 131I-MIBG by radioiodination of meta-diazobenzylguanidine, and compares this process with one involving iododesilylation of meta-trimethylsilylbenzylguanidine. Both processes result in the formation of carrier-free 131I-MIBG whose specific activity at greater than 3 x 10(16) Bq mol-1 is at least 100 times higher than that of commercially available 131I-MIBG for therapeutic use. The therapeutic use of 131I-MIBG with a higher than usual specific activity is predicted to result in a greater target-to-nontarget ratio, and therefore enhanced efficacy because of an increased therapeutic index. As the radiochemical yield of the process involving the metadiazobenzylguanidine intermediate is only 13%, compared with 98% for the iododesilylation reaction, the latter is the preferred synthetic route.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Iodobenzylguanidine
  • Benzylamines / chemistry
  • Chemical Phenomena
  • Chemistry, Physical
  • Chromatography, High Pressure Liquid
  • Diazonium Compounds / chemistry*
  • Gas Chromatography-Mass Spectrometry
  • Guanidine
  • Guanidines / chemistry*
  • Iodine Radioisotopes / chemistry*
  • Iodobenzenes / chemical synthesis*
  • Iodobenzenes / chemistry
  • Magnetic Resonance Spectroscopy
  • Radiochemistry
  • Trimethylsilyl Compounds / chemistry*


  • 3-diazobenzylguanidine
  • Benzylamines
  • Diazonium Compounds
  • Guanidines
  • Iodine Radioisotopes
  • Iodobenzenes
  • Trimethylsilyl Compounds
  • 3-trimethylsilylbenzylguanidine
  • 3-Iodobenzylguanidine
  • 3-nitrobenzylamine
  • 3-aminobenzylguanidine
  • 3-nitrobenzylguanidine
  • Guanidine