The influence of irradiation on drugs and drug additives

In this study, the results obtained by experimental irradiation of 60 drugs and drug - additives of different types are reported and discussed. The substances were irradiated in pure form, as aqueous solutions with and without protective additives as well as seperately from the solvent (preparation of the solutions using seperately irradiated components); the radiation being almost exclusively γ-radiation from cobalt - 60 - sources. The applied radiation doses ranged between 0,05 and 100 Mrad or Mr. For the dose range which is relevant in radiation sterilization (approx. 1 - 5 Mrad) the results show the following tendencies: 1) In about 70% of the experiments, irradiation of pure substances showed no decomposition of the drugs or drug - additives, the greater part of the rest being decomposed only to a small extent. 2) In aqueous solutions irradiation caused with rare exceptions a more or less strong radiolysis in all solved pharmaceutical substances. Decomposition occured specifically according to the substances; it increased somewhat exponentially with decreasing concentration of the solution and almost linearily with increasing dose. 3) The decomposition rates of eye drops are similar to those of aqueous solutions. In some cases, the added agents may have a somewhat protective effect. 4) Addition of sodium pyrosulphite to the solutions did not always have a stabilizing effect on the drugs. 5) In the solutions consisting of seperately irradiated components, a decomposition could be proved only if the irradiated pure substances already contained radiolysis products. (orig./MG)