Rheological effect of gamma radiation on gel-like formulation: Appraisal for the construction of radiopharmaceuticals for cutaneous application

Skin cancer affects a lot of people being a malignant cutaneous melanoma one of the most aggressive neoplasms. Nowadays, the FDA-approved drugs to treat them are not as efficient as needed. Thus, the development of new agents or treatments is quite urgent. In that sense, the use of radioactive materials could represent a good alternative and especially Radium-223 is already been explored with promising results. Here, a Carbopol gel-like formulation was designed and irradiated with different doses in order to prove that it is suitable to include Radium-223 for its combined application by topic route. A formulation was obtained by the addition of triethanolamine to the Carbopol solution until pH 5.0. Physical and rheological tests showed that the formulation is a weak gel with a proper consistence to be administered by both routes. The formulation kept its appearance of transparent gel without change in color, presence of grits or syneresis after all tratments. The microstructure of gels was only slightly modified when the irradiation was made with 1000 Gy while the spreadability and viscosity were more deeply affected. Since the properties of this Carbopol gel-like formulation were maintained under irradiation doses until 100 Gy it is possible to consider that the formulation is suitable to include Radium-223 in order to evaluate its performance as localized drug delivery system for topical administration.