Preparation of a radionuclide/gel formulation for localised radiotherapy to a wide range of organs and tissues.

Localised radiotherapy by instillation of radiolabeled particles is being used to treat rheumatoid arthritis and certain tumors. Such therapy is limited to organs and tissues capable of retaining the radioactive compound until the radioactivity is sufficiently low, and the leakage to other parts of the body is no longer unacceptable. In this study, radiolabeled particles, i.e. 90Y-silica colloid particles, were encapsulated in calcium alginate gels, and the leakage of radioactivity from the gels was monitored. The purpose of the study was to develop a formulation suitable for the localised delivery of radiation therapy to a wide range of organs and tissues. An injectable gel formulation was developed, liberating only small amounts of radioactivity into the surrounding medium. The formulation is a viscous liquid at room temperature and forms a gel on heating to normal body temperature. Thus, it should be suitable for the localised delivery of radiolabeled particles to a wide range of organs and tissues. The study also includes a formulation exhibiting time-dependent gelation. However, this formulation was not found to be suitable for the purpose.