"In-house" preparation of 99mTc-EDDA/HYNIC-TOC, a specific targeting agent for somatostatin receptor scintigraphy

• Main Authors: Sonja Kuzmanovska (Author), Olivija Vaskova (Author), Marina Zdraveska Kocovska (Author)
• Format: Book
• Published: University Ss Cyril and Methodius in Skopje, Faculty of Pharmacy and Macedonian Pharmaceutical Association, 2012-01-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1409-8695; 1857-8969
• Keywords: Pharmacy and materia medica; RS1-441
• Source: Makedonsko Farmacevtski Bilten, Vol 57, Iss (1, 2), Pp 65-70 (2012)

The use of radiolabeled peptide ligands as diagnostics and therapeutics in nuclear oncology has increased recently. One of the most frequently used radiopharmaceutical is 99mTc-EDDA/HYNIC-TOC, a somatostatin analog with affinity for certain types of somatostatin receptors, overexpressed in tumors of neuroendocrine origin. The radiopharmaceutical is not readily available; therefore we introduced its "in house" preparation within project activities supported by the International Atomic Energy Agency (IAEA). We optimized the radiolabeling protocol, prepared a small batch of frozen kits, performed ITLC quality control and animal biodistribution during the preclinical evaluation procedures. The co-ligand exchange labeling procedure was carried out at 100°C during 10 min, resulting in radiochemical purity >90%. The biodistribution scintigrams in normal Wistar rats showed rapid blood clearance after 15 min and predominant kidney accumulation after 4 h, in accordance with the data reported by other authors. Storage stability of the formulated small batch frozen kit (-20°C) was evaluated within 6 months, with radiolabeling yield ranging between 94,3% and 96,9%. We conclude that frozen kit can be a safe alternative to the freeze-dried for small batch in house production, and after the satisfactory preclinical evaluation, the "in house" prepared 99mTc-EDDA/ HYNIC-TOC can be introduced in clinical practice as specific targeting agent for somatostatin receptor scintigraphy.