## 1 Introduction  
The antibiotics detected in hospital, municipal and industrial pharmaceuticals wereaters can lead to selective proliferation of some microorganisms [1, 2], and thus their removal from different contaminated resources has become a concern, in recent years, for many researchers [1, 2]. Qualitative and quantitative analyses of cephalosporon antibiotics sometimes involve certain impediments due to their complex physical and chemical features. For the analysis of bulk drugs and pharmaceutical compounds contained by biological fluids or wastewaters, spectroscopic, chromatographic and electrochemical methods were reported to be effective [3, 4, 5, 6, 7]. Antibiotics are partially metabolized in non-toxic compounds, but often drugs are eliminated as such, having a negative impact on the environment and causing its pollution. The biological release of drugs and their degradation compounds could lead to contamination of surface waters and sediments [8]. Based on antimicrobial properties, the cephalosporons can be classified into the first, second, third and fourth generation. According to this classification, ceftaxone is the third-generation agent produced by the Fungus Cephalosporinum acromonium, a class of \(\beta\)-lactam type, used to inhibit the bacterial wall cell synthesis. Indirect determination of ceftriaxone using n-propyl alcohol--ammonium sulfate, by extraction or by riboflavin sensitization, represents new ways for its spectrophotometric determination or photooxidation [9; 10]. Sonoelectrochemical catalytic degradation onto a nanocoated electrode led to a drug removal efficiency of 94%, at a current density of 8 mA\(\cdot\)cm\({}^{-2}\) and an ultrasound frequency of 45 kHz [11]. Optimizing of experimental parameters of photo-induced and sonocatalytic degradation revealed a ceftaxone removal efficiency ranging between 70% and 95% [12; 13; 14; 15; 16]. These methods were also used for ceftaxone degradation in the presence of carbon nitride (g-C\({}_{3}\)N\({}_{4}\)) and different composite materials such as Ag-CsPbBr\({}_{3}\), ZnSe, BiWO\({}_{6}\)[17; 18; 19; 20; 21]. Indirect electrochemical oxidation was applied for decomposition of biologically active compounds such as vitamins, antibiotics, food additives and pesticides, reaching a good removal performance of these contaminants from wastewaters [22; 23; 24; 25; 26; 27; 28]. A new possibility to enhance the degradation degree of ceftaxone implies the controlled synthesis of nanostructured photocatalysts as BiWO\({}_{6}\) nanoflowers, SnO\({}_{2}\)-TiO\({}_{2}\)/nano-graphite, TiO\({}_{2}\)/nano-graphite, RuO\({}_{2}\)-TiO\({}_{2}\)/nano-graphite [29; 30; 31; 32]. A very important aspect of the pharmaceutical chemistry field consists of the investigation of drug interactions in multicomponent systems that can facilitate decomposition/degradation or transformation into other compounds with adverse and unfriendly effects on the human body. Unwanted drug interactions can also lead to a decrease in the expected effect for which the drug was administered. Medicines/food supplements containing bromine, chlorine, iodine or fluorine can induce partial inactivation of other concomitantly administered drugs due to their interactions with halogen ions which catalyzes the degradation/transformation of the respective pharmaceutical compounds. In the aforementioned context, in this work, the electro(degradation/transformation) of ceftaxone (CFTX) was investigated, following two objectives: (i) removal of drug traces from medical wastewater; (ii) the effect of anions of fluoride, chloride, bromide and iodide on the CFTX stability, in aqueous solutions, at a pH close to neutral and at room temperature. Normal administration and storage conditions were chosen to avoid the introduction into the reaction media of other substances that could cause additional interactions. The CFTX electrochemical degradation/transformation on a platinum electrode was investigated by cyclic voltammetry and constant current electrolysis assisted by UV-Vis spectrophotometry.