Quality control of iodine-131-labeled metaiodobenzylguanidine.

AIM/OBJECTIVES/BACKGROUND: Iodine-131-m-iodobenzylguanidine ([(131)I]mIBG) is used worldwide for the diagnosis and therapy of neuroendocrine tumors, particularly adrenal medullae tumors. After the synthesis and preparation of a radioiodinated MIBG drug formulation, quality control testing to determine its radiochemical purity (RCP) should be performed. European Pharmacopoeia 8.0 requires that the quality control include a test for RCP for the determination of [(131)I]mIBG. Previously reported procedures using reversed-phase conditions require long retention times. Our system enables the separation of [(131)I]mIBG within a few minutes. The aim of this work was to carry out RCP testing for [(131)I]mIBG without any type of sample pretreatment. METHODS: RCP testing for ([(131)I]mIBG has been carried out using high-performance liquid chromatography and thin-layer chromatography methods. RESULTS: A simple and rapid reversed-phase isocratic system enables the HPLC investigation of RCP testing for [(131)I]mIBG used for therapy within a few minutes. CONCLUSIONS: From the point of view of radiation protection, this method is safer, especially for therapeutic amounts of [(131)I]mIBG.

Preparation of poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels and their drug release behavior.

N-isopropylacrylamide/itaconic acid copolymeric hydrogels were prepared by irradiation of the ternary mixtures of N-isopropylacrylamide/itaconic acid/water by gamma-rays at ambient temperature. The effect of comonomer concentration, irradiation dose and pH on the swelling equilibria were studied. Lidocaine was used as a model drug for the investigation of drug release behaviour of hydrogels. Lidocaine adsorption capacity of the hydrogels were found to increase from 3.6 to 862.1 (mg lidocaine/g dry gel) with increasing amount of itaconic acid in the gel structure. Adsorption and release processes were followed at 4 and 37 degrees C, respectively. The release studies showed that the basic parameters affecting the drug release behaviour of the hydrogels were pH and temperature of the solution and cross-link density of the gels.