Preliminary Assessment of Tc-Salmeterol Xinafoate as a Potential Bone Imaging Agent

Sameterol xinafoate is a selective β2-adrenoceptor agonist used in the treatment of some lung diseases and play a vital role in the regulation of bone mass and bone turnover. Tc-salmeterol was formulated for the development of a novel potential diagnostic bone imaging agent with excellent biological properties. Factors influencing the labeling yield such as salmeterol xinafoate amount, pH of the reaction medium, reducing agent amount and the reaction time were studied in details. Tc-salmeterol was obtained with a high radiochemical yield of 94.6±0.5% and in vitro stability of 6 h when 0.5 mg of salmeterol was mixed with 10 mg NaBH4 at pH 9 and a reaction time 30 min. The biological distribution showed that Tc-salmeterol was highly concentrated in the bone (36.5 ± 2%ID/organ) at 30 min post injection. The bone uptake of Tc-salmeterol was remained high (29.3 ± 2ID/organ) for a time up to 2h post injection. The results revealed that Tc-salmeterol could solve the Tc-phosphonate drawbacks and could be used as a bone imaging agent.