Abstract

In this research, electrochemical oxidation of acetaminophen was investigated in the presence of steroidal anti-inflammatory drugs diclofenac and piroxicam by cyclic voltammetry and controlled-potential coulometry techniques. The results indicated that N-acetyl-p-benzoquinone-imine (NAPQI), produced by electrooxidation of acetaminophen, reacts with diclofenac and piroxicam, via the Michael addition reaction. Corresponding products were electrochemically synthesized in aqueous solutions using a carbon electrode in an undivided cell. These products were identified by spectroscopic methods (FT-IR, 1HNMR, 13CNMR and MS). The homogeneous rate constants (kobs), based on the suggested electrode mechanism (i.e. EC), were estimated by comparing the experimental cyclic voltammetric responses with those digital simulated results. A comparison of the estimated kobs for the reaction of electrochemically generated N-acetyl-p-benzoquinone-imine (NAPQI) with steroidal anti-inflammatory drugs revealed that kobs (piroxicam) > kobs(diclofenac) at biological pH.