99mTc labelled peptide for imaging of peripheral receptors

Conjugates of somatostatin analogues, RC-160 with different bifunctional chelators to label with 99mTc, were synthesized. Conjugates with hydrazinonicotinamide (HYNIC) and compounds (benzoyl MAG-3 and CITC-DTPA) were prepared on a small scale with high purity and evaluated as different types of chelators on RC-160. Stability studies performed under physiological conditions showed high stability. Peptide conjugates could be labelled at high specific activities (307inCi/umol) with 99mTc and different transchelator were used for the HYNIC conjugates. The resulting radiolabelled with (99mTc and 1251) complexes were highly stable and showed binding affinity to somatostatin receptors in the nanomolar range. The radioconjugates were administered to rabbits and mice in order to study their in vivo stability, biokinetics and biodistribution. (author)