Fast efficient method for radiolabeling of pindolol with iodine-125 using iodogen coated glass frit

Although 125I-hydroxypindolol (125I-HYP) has been an excellent probe of adrenoceptor function in certain tissues, but 125I-pindolol (125I-PIN) was found more specific for β-adrenoceptor labeling. A fast and efficient method for radiolabeling of pindolol with iodine-125 is described where both chloramine-T and iodogen were used as oxidizing agents. The use of iodogen coated glass frit has a great advantage in increasing the radiochemical yield of 125I-pindolol and this was attributed to the increase of the interfaces boundary between the solid and liquid. This technique reduces the quantity of iodogen required to produce high radiochemical yield by its half. The radiochemical yield was determined by TLC system using chloroform: acetic acid: water (15:4:1) as developing solvent and by HPLC using reversed phase RP-18 column and acetonitrile: 0.1 M ammonium bicarbonate pH 7.5 (1:1) as a mobile phase at flow rate (1ml/min). The radiochemical yield was found to be 48.6 and 62.9% respectively. (author)