Comparative biological evaluation between 99mTc tricarbonyl and 99mTc-Sn(II) levosalbutamol as a β 2-adrenoceptor agonist

Abstract

Abstract This study describes the comparison between 99mTc-tricarbonyl and 99mTc-Sn (II) levosalbutamol as a β 2-adrenoceptors radiopharmaceutical and evaluation of their different biological characteristics using experimental animals. Levosalbutamol was labeled firstly with 99mTc in the presence of SnCl2 · 2H2O as a reducing agent under the optimum conditions: pH 8, 50 μg SnCl2 · 2H–2O, room temperature, 40 μg levosalbutamol and 30 min reaction time to give a maximum radiochemical yield of 98 ± 0.1%. The obtained 99mTc-levosalbutamol was stable for a time up to 8 h. Secondly, 99mTc-tricarbonyl ([99mTc(CO)3(H2O)3]+) levosalbutamol was prepare under 30 min heating at 100 ℃. Labeling yield and stability were analyzed by high performance liquid chromatography (labeling yield >99% and stability for 8 h). Biodistribution investigation showed that, the maximum uptake ratio of the 99mTc-levosalbutamol (99mTc-Lev) between lung and heart was 2.34 ± 0.62 % of the injected activity/g tissue organ, at 30 min post-injection. But in case of 99mTc-tricarbonyl levosalbutamol (99mTc-tricarbonyl Lev) the maximum uptake ratio was 3.6 ± 0.11of the injected activity/g tissue organ, at 30 min post-injection. This indicates that 99mTc-tricarbonyl levosalbutamol was more selective for lung β 2-adrenoceptors than 99mTc-levosalbutamol. These results introduce 99mTc-tricarbonyl levosalbutamol as a novel potential radiopharmaceutical for lung imaging.