Development of a freeze-dried kit formulation for the preparation of 99mTc-NTP 15-5, a radiotracer for scintigraphic imaging of proteoglycans

• Synthesis and radiolabeling of 99mTc-NTP 15-5.
• A lyophilized kit was successfully developed for preparation of 99mTc-NTP 15-5.
• High storage stability of NTP 15-5 kit.
• 99mTc-NTP 15-5 resulted in favorable biological evaluations.

The cartilage-targeting strategy is based on the strong affinity of quaternary ammonium (QA) functions for cartilage proteoglycans. We use a bifunctional agent containing QA moiety and a polyazamacrocycle structure able to complex technetium-99m. 99mTc-NTP 15-5 was selected for its high stability and its high affinity for proteoglycans in vivo. Labeling conditions of NTP 15-5 were optimized, and a lyophilized kit was developed for radiolabeling of 99mTc-NTP 15-5 (radiochemical yields 94.6±1.8%). 99mTc-NTP 15-5 was stable and resulted in favorable biological evaluations.