Classical methods of wastewater treatment are often not suitable for the treatment of pharmaceutical waste. The previous studies have shown that the use of the advanced oxidation procedures (AOP) can lead to a more efficient degradation of various biologically active compounds, which are active pharmaceutical ingredients of applied drugs. The aim of this paper is the application of the plasma technology on the degradation of a two active pharmaceutical ingredients (APIs, diazepam and alprazolam) and the finished products (Bensedin ® and Ksalol ®) using the dielectric barrier discharge (DBD) reactor for AOP. We studied the degradation rate of these pharmaceuticals, depending on the number of passes through the reactor. This degradation method was efficient 61 % for diazepam and 95 % alprazolam. We also examined the influence of the pH adjustment between the passes of APIs through the DBD reactor. The degradation rate of APIs and the finished products was monitored by the high performance liquid chromatography (HPLC) technique, using a photodiode array detector. The concentration of the dissolved ozone was determined using the iodometric procedure.