Application of 99Mo/99mTc alumina generator in the labeling of metoprolol for diagnostic purposes

Labeling of metoprolol by technetium‐99m in pertechnetate form (^99mTcO) eluted from a ⁹⁹Mo/^99mTc alumina generator in the presence of stannous chloride dihydrate was carried out via chelation reaction. The reaction parameters that affect the labeling yield such as metoprolol concentration, stannous chloride dihydrate concentration, reaction temperature, and pH of the reaction mixture were studied to optimize the labeling conditions. Using 1 GBq ^99mTcO, 500 µg metoprolol as substrate dissolved in 500 µL phosphate buffer at pH 9 and 50 µL of stannous chloride as reducing agent (1 mg/mL) at 25°C for 30 min reaction time, a maximum radiochemical yield of ^99mTc‐metoprolol (92%) was obtained. ^99mTc‐metoprolol was characterized by thin layer chromatography (TLC) and by high pressure liquid chromatography (HPLC). The specific activity of ^99mTc‐metoprolol obtained was 888 MBq/1.88 mmol. The biological distribution in normal mice showed that ^99mTc‐metoprolol is rapidly concentrated after injection in the heart, which indicates its suitability for heart imaging. Copyright © 2009 John Wiley & Sons, Ltd.