The group of new pollutants that have been bioaccumulated in the environment by human activity in the last seventy years includes plastics and pharmaceuticals. They belong to the groups of synthetic stable organic compounds resistant to biological and photolytic degradation. In the environment plastic is degraded to smaller microplastic particles which adsorb pharmaceuticals. In the mutual interaction they circle in the Earth's geosphere and biosphere and represent a global ecological health problem. Conventional wastewater treatment methods do not allow the successful removal of such contaminants before they are discharged into natural receivers. In order to improve the efficiency of their removal from wastewater, it is necessary to investigate their interactions and develop new methods that adapt and supplement existing ones. One of them is the Advanced Oxidation Process (AOP). The purpose of this thesis is to perform preliminary investigation into the interaction of microplastic particles of polyethylene (PE) and polyvinyl chloride (PVC) with donepezil hydrochloride (DNP) and its degradation. Donepezil hydrochloride was subjected to forced degradation processes and advanced oxidation processes with hydrogen peroxide (UV/ H2O2) and persulfate (UV/S2O82-7) in the presence of PE and PVC microplastics. Based on the obtained data, it was determined that the degradation of DNP is kinetic reaction of first order. DNP is a very stable compound that is difficult to degrade. The influence of process parameters pH value, oxidant concentration and microplastic concentration was successfully estimated using Box-Behnken factor design experiment and RSM model was developed. Based on the coefficient of determination (R2) and analysis of variance (ANOVA), the accuracy of the model was estimated. In order to assess the influence of experimentally obtained process parameters (pH values, oxidant concentrations and microplastic concentrations) on the degradation rate of pharmaceutical DNP, RSM models were developed and the optimal process conditions are determined. All designed models are significant and have shown good accuracy. Degradation of DNP processes by UV/H2O2-PE is influenced by all process parameters. Optimal degradation conditions were determined for the UV/Na2S2O8-PVC process at c(Na2S2O8) = 10 mM, pH = 4, c(PVC) = 10mM with a conversion of 11.11%. The pharmaceutical DNP is stable over a wide pH range and has low affinity for PE and PVC microplastic particles.