ABSTRACT
Background: in this study, human absorbed dose of a newly introduced bone imaging agent, 68Ga-[4-[[[bis[phosphonomethyl]]carbamoyl]methyl]-7,10-bis [carboxymethyl]-1,4,7,10-tetraazacyclododec-1-yl] acetic acid [68Ga-BPAMD], was estimated based on the rats data
Materials and Methods: 68Ga was obtained from the 68Ge/68Ga generator and it's radionuclidic and radiochemical purities were investigated. 68Ga-BPAMD complex was prepared at optimal conditions and the radiochemical purity was studied using instant thin layer chromatography [ITLC] method. The final preparation was injected to the normal rats and the biodistribution of the complex was followed up to 120 min post injection. The accumulated activity for animal organs was calculated. Finally, the human absorbed dose of the complexes was estimated by RADAR Method
Results: 68Ga-BPAMD complex was prepared in high radiochemical purity [>99%, ITLC] at optimal conditions. The biodistribution of the complex demonstrated that the main remained radioactivity would considerably accumulate into the bones. The results showed the highest amounts of absorbed dose on the bone surface [0.253 mGy/MBq] and in the bone marrow [0.250 mGy/MBq], while the other organs would receive an insignificant absorbed dose after injection of the 68Ga-BPAMD complex
Conclusion: the comparison of dosimetric results for 68Ga-BPAMD with other complexes shows this complex is a safer agent for bone scanning. This property as well as other characteristics such as the high resolution images of the positron emission tomography [PET] scanning and the availability of 68Ga in the form of 68Ge/68Ga generator, make this complex as a suitable agent for PET bone imaging
ABSTRACT
Chlorotoxin is a 36-amino acid peptide found in the venom of the Leiurus quinquestriatus which blocks small-conductance chloride channels. Chlorotoxin binds preferentially to glioma cells that allow development of new methods for the treatment and diagnosis of several types of cancer. Thus chlorotoxin derivative was labeled with [131]I for further investigation. A chlorotoxin derivative was synthesized on a solid phase using a standard Fmoc strategy. Labeling with iodine-131 was performed through chloramine-T method and radiochemical analysis involved sephadex G-25 and HPLC methods. The stability of radiopeptide was checked in the presence of PBS and human serum at 37 °C up to 24 h. The biodistribution was studied in mice. The chemical purity of synthesized peptide as assessed by analytical RP-HPLC was 95%. Labeling of peptide resulted in a radiochemical yield of 80% with radiochemical purity of > 95% with specific activity of 0.740 GBq/ micro mol. Result of in vitro studies demonstrated acceptable stability of compound in human serum and PBS solution. Biodistribution data showed moderate blood clearance, with concentration of radioactivity in the kidneys, liver, intestine and stomach. Results indicates that the labeled Chlorotoxin derivative might be useful in determining tumor extent and also, tumor therapy of gliomas or possibily other cancers