[The effect of fluorine substituent on radiochemical stability of some steroid and azole derivatives].

Radiochemical stability of three fluorine containing therapeutic substances: dexamethasone, fludrocortisone acetate (steroid derivatives) and fluconazole (azole derivative) has been studied. The compounds in the solid phase were exposed to ionising radiation in the form of electron beam using doses of 20-400 kGy. The inital and irradiated compounds were subjected to comparative analyses by organoleptic, spectrophotometric (UV and IR) and chromatographic (TLC and HPLC) methods. For all compounds studied the irradiation was found to lead to a decrease in the active substance content (HPLC), appearance of radiolysis products (TLC), changes in the physical and chemical properties such as colour (fluconazole), formation of agglomerates (dexamethasone), decrease (dexamethasone, fludrocortisone acetate) or increase in UV absorption (fluconazole). The two steroid derivatives were found resistant to ionising radiation at doses of 25-50 kGy and can be sterilised by radiation, whereas fluconazole was too sensitive to electron beam irradiation and should be sterilised by other methods. The results were compared with those of earlier studies on radiation sterilisation of other steroid derivatives. An interesting conclusion is that the presence of the fluorine atom in the molecule of fludrocortisone acetate has no significant effect on its radiochemical stability when compared with that of hydrocortisone acetate--the analogue without fluorine.