HPLC detection and quantification of radiolytic products of eight beta-blockers irradiated in the solid state and hypotheses on their origins.

PURPOSE: The radiolytic products of eight beta-blockers were studied in order to understand the mechanisms of irradiation of drugs in the solid state. METHODS: The drugs were analyzed by high-performance liquid chromatography coupled to a diode array detector in order to observe the degradation of the main compound after irradiation and in order to study the nonvolatile final products on more concentrated solutions of irradiated drugs. RESULTS: The first test assessed that the main compound was not significantly degraded after gamma irradiation for any of the eight beta-blockers. A more complete study, which consisted on separating the nonvolatile products and on quantifying them, indicated first that the radiolytic products could reach the number of 14 and moreover that some could exceed the 0.1% threshold at 30 kGy. Eventually, radiolytic yields were compared with radical yields previously determined. CONCLUSIONS: The sensitivity of the first test can be discussed. It seems that, to study the feasibility of the radiosterilization, a complete study of the products of degradation is needed. Moreover, no correlation between radical and final products could be established, which denies that the former would be the precursors of the latter