Dry state preparation of radioiodine labeled meta-iodobenzylguanidine

Abstract

Radioiodination of meta-iodobenzylguanidine (MIBG) by the isotopic exchange technique in the dry state has been performed. Benzoic acid, pivalic acid and acetamide have been used as molten protic media to promote isotopic exchange reactions. Ammonium sulphate, diammonium hydrogen ortho-phosphate and ammonium chloride were used as catalysts which provide acidic media to facilitate exchange reactions. Maximum radiochemical yields of 97.1+1.3% and 84.3+1.6% [1311] MIBG were obtained when ammonium sulphate and benzoic acid were used. High radiochemical yields of 88.3+1.1% and 74.4+1.5% 11311] MIBG were also obtained in case of diammonium hydrogen orthophosphate and pivalic acid which suggests their successful use as reaction media in the radioiodination of MIBG. The activation energy for the exchange reaction in ammonium sulphate was calculated to be 10.8 kcal/mole.

Radioiodination of 4-benzyl-1-(3-iodobenzylsulfonyl)piperidine, 4-(3-iodobenzyl)-1-(benzylsulfonyl)piperazine and their derivatives via isotopic and non-isotopic exchange reactions

“…The Table 1 [17,[31][32][33]. The results indicate that the exchange reaction does not occur by mixing of precursor and Na 125 I at elevated temperature (entry 1) only, but also in presence of ammonium sulfate (entry 2) as an agent increases the acidity of the reaction medium.…”

“…Moreover, radioiodination is achieved in solid phase at high temperature and using in some cases the salts of Cu(I) and Cu(II) as catalysts or molten salts such as benzoic acid [15,16], acetamide, ammonium sulfate, pivalic acid, citric acid and acetic acid, which have high dielectric constant to dissolve both of the substrate and radioiodine [10,13,17,18]. In some cases the molten salts are not effective for radioiodination of some organic compounds.…”

Establishment of a fast and high yield method for routine production of [131I]MIBG and investigation of its radiochemical stability for diagnosis and treatment uses

“…As an example of the modified reaction, ascorbic acid or sodium metabisulfite was used to accomplish the generation of Cu(I). These synthetic methods have produced varying radiochemical yields, which in some cases have been close to quantitative . However, these values were attained only with limited amounts of radioactivity, The objective of the present work was the development of a reliable method to facilitate large‐scale production of [ 131 I]MIBG for general distribution.…”