Biodistribution study of [^(61)Cu]pyruvaldehyde-bis (N-4-methylthiosemicarbazone) in normal rats as a PET tracer

[61Cu]-labeled pyruvaldehyde-bis(N-4-methylthiosemicarbazone) (61Cu-PTSM), a promising agent made for imaging blood perfusion, was produced via the natZn(p,x)61Cu nuclear reaction in a 30 MeV cyclotron, and separated by a two-step column chromatography method developed in our laboratory using a cation and an anion exchange resin. After 150 μA irradiation for 76 min, about 6.006 Ci of 61Cu2+ was obtained with a radiochemical separation yield of 95% and a radionuclidic purity of 99%. Cu-PTSM was prepared using an optimized method with 61 in-house synthesized PTSM ligand for radiolabeling following quality control procedures using RTLC and HPLC. The tracer is mostly incorporated in heart, kidneys and brain compared to free copper cation as a control. These are in agreement with former reports. In conclusion, [61Cu]-PTSM was prepared at the radiopharmaceutical scales with high quality and is a potential PET tracer in the perfusion study of the heart, kidney, brain and tumors.

Preparation and biodistribution assessment of 68Ga-DKFZ-PSMA-617 for PET prostate cancer imaging

Prostate-specific membrane antigen(PSMA) is a useful target for diagnostic and therapeutic applications,and it is demonstrated that ^(68) Ga in conjugation with DKFZPSMA-617 is better than ^(68)Ga-PSMA-1 in biodistribution data after 1 h,but more preclinical data are still required.In this paper,we presented the additional preclinical data for ^(68)Ga-DKFZ-PSMA-617 and relevant aspects of its production.^(68) Ga was obtained from the SnO_2-based ^(68)Ge/ ^(68) Ga generator.Optimum conditions(p H,temperature,time and ligand concentration) for ^(68)Ga-DKFZPSMA-617 preparation were studied.Radiochemical purity of the radiolabeled compound was determined by HPLC and RTLC.After stability assessments,the complex was intravenously injected into rats.HPLC and ITLC characterizations indicated that the radiopharmaceutical could be prepared with radiochemical purity of [96 % and specific activity of 308.3 TBq/mmol at the optimized conditions(p H of 3.5–4,ligand amount of 2.4 nmol,temperature of90–95 C and reaction time of 10 min).Also,the biodistribution data showed no undesirable uptake in nontarget organs at any interval after injection.In fact,the activity is cleaned from blood and excreted rapidly via the kidneys.Generally,this compound can be considered as a wellestablished PET imaging agent.

Dose evaluation of therapeutic radiolabeled bleomycin complexes based on biodistribution data in wild-type rats:Effect of radionuclides in absorbed dose of different organs

Bleomycins(BLMs), as tumor-seeking antibiotics, have been used for over 20 years in treatment of several types of cancers. Several radioisotopes are used in radiolabeling of BLMs for therapeutic and diagnostic purposes. An important points in developing new radiopharmaceuticals, especially therapeutic agents, is the absorbed dose delivered in critical organs. In this work, absorbed dose to organs after injection of ^(153)Sm-,^(177)Lu- and ^(166)Ho-labeled BLM was investigated by radiation dose assessment resource(RADAR) method based on biodistribution data in wild-type rats. The absorbed dose effect of the radionuclides was evaluated. The maximum absorbed dose for the complexes was observed in the kidneys, liver and lungs. For all the radiolabeled BLMs,bone and red marrow received considerable absorbed dose. Due to the high energy beta particles emitted by ^(166)Ho, higher absorbed dose is observed for ^(166)Ho-BLM in the most organs. The reported data can be useful for the determination of the maximum permissible injected activity of the radiolabeled BLMs in the treatment planning programs.

Preparation and preliminary evaluation of [^(55)Co](II)vancomycin

Co-55 (t1/2=17.53 h) was produced by 150 μA irradiation of a natural nickel target using 15 MeV protons. It was separated from the irradiated target material by two ion exchange chromatography steps with a radiochemical yield of >95% and was used for the preparation of [55Co]vancomycin ([55Co]VAN). Optimization studies were per- formed using Co-57 due to its longer half-life. Cobalt-57 (t1/2=271.79 d) was produced by irradiation of a natural nickel target with 150 μA current of 22 MeV protons. The 57Co was separated from the irradiated target material using a no-carrier-added method with a radiochemical yield of >97%. Both products were controlled for radionuclide and chemical purity. The solutions of [55Co]VAN were prepared (radiochemical yield>80%) starting with 55Co acetate and vancomycin at room temperature after 30 min. A precise solid phrase extraction (SPE) method was developed using Si Sep-Pak in order to purify/reconstitute the final formulation for animal studies. [55Co]VAN showed a radiochemical purity of more than 99%. The resultant specific activity was about 1.15 TBq/mmol. It is proved that the tracer is stable in the final product and in presence of human serum at 37°C up to 24 h. Biodistribution study of [55Co]VAN in normal rats was undertaken for up to 72 h.