Evaluation of (99m)Tc-labeled photosan-3, a hematoporphyrin derivative, as a potential radiopharmaceutical for tumor scintigraphy.

Abstract

A quick and reproducible method for radiolabeling of Photosan-3(R), a photosensitizer used worldwide for photodynamic therapy (PDT) of cancer, with radioisotope of technetium ((99m)Tc) was developed. The radiotracer was evaluated for radiochemical purity, stability, and finally tissue distribution in a murine tumor model. The (99m)Tc-Photosan-3 prepared by using (99m)Tc-pertechnetate in place of reduced (99m)Tc demonstrated better labeling efficiency (>90%) and reproducibility. The procedure also minimized the radiation exposure to the radiochemist as handling time was considerably reduced. Due to the commercial availability of Photosan-3, the risk of batch-to-batch variation in the in situ synthesis of hematoporphyrin derivative, which is a complex mixture of at least five compounds, was also significantly reduced. The biodistribution studies and tumor scintigraphy confirmed that (99m)Tc-labeled Photosan-3 was preferentially taken up by the neoplastic tissue in a manner similar to the parent compound. In addition to applications in tumor imaging, (99m)Tc-Photosan-3 could also be used for estimating tumor uptake of Photosan-3 as may be required for individualization of clinical protocols of PDT.

• Authors: A K Babbar, A K Singh, H C Goel, U P Chauhan, R K Sharma
• Journal: Nuclear medicine and biology (Nucl Med Biol) Vol. 27 Issue 6 Pg. 587-92 (Aug 2000) ISSN: 0969-8051 [Print] United States
• PMID: 11056374 (Publication Type: Evaluation Study, Journal Article)

Chemical References

• Hematoporphyrins
• Photosensitizing Agents
• Radiopharmaceuticals
• Tin Compounds
• photosan III
• stannous chloride
• Technetium
• Sodium Pertechnetate Tc 99m

Topics

• Animals
• Carcinoma, Ehrlich Tumor (diagnostic imaging, metabolism)
• Disease Models, Animal
• Drug Evaluation, Preclinical
• Drug Stability
• Hematoporphyrins (chemistry, pharmacokinetics)
• Metabolic Clearance Rate
• Mice
• Neoplasm Transplantation
• Organ Specificity
• Photosensitizing Agents (chemistry, pharmacokinetics)
• Rabbits
• Radionuclide Imaging
• Radiopharmaceuticals (chemistry, pharmacokinetics)
• Reproducibility of Results
• Sodium Pertechnetate Tc 99m (chemistry)
• Technetium (analysis, chemistry)
• Tin Compounds (chemistry)
• Tissue Distribution