Analysis of structural defects caused by gamma radiation on some medicines through electron paramagnetic resonance and simulation techniques

My thesis study comprises an investigation on changes in the amount and stability of the free radicals, produced by gamma irradiation of five different drug types, depending on the radiation absorbed. Drug samples used in the study were irradiated at dose levels between 1-25 kGy at room temperature. While no Electron Paramagnetic Resonance (EPR) signal was observed in non-irradiated samples, irradiation dose-dependent signals were observed in irradiated samples. Firstly, microwave saturation power of the drug samples at room temperature was examined. Among many functions that define the dose-response curves of the irradiated samples, the functions that define these curves the best were identified. EPR signals were examined and correlation coefficients that determine the consistency between the absorbed dose and signal intensity were identified. The reactions of the drugs, which were irradiated at a dose of 25 kGy, to ignition and infrigidation at various temperature ranges were evaluated and interpreted. Rates of change in the signal intensities of the samples kept for five months were calculated. EPR spectrums of all samples were obtained using Mc Kelvey simulation program. Paramagnetic centers and g values of the samples were calculated. Keywords: Electron Paramagnetic Resonance (EPR), Medicine,Radiation, Dosimeter, Mc Kelvey