Mefenamic acid (MFA) is a member of fenamate group of non- steroidal anti-inflammatory drug used in the therapy of pain phenomena and blockade of inflammatory areas; for the stimulation of the immune system in patients with arthritis and arthrosis. The degree of menstrual blood loss is reduced with the treatment of MFA and it is also used to treat autoimmune haemolytic anaemia. Measurement of plasma levels of MFA may provide valuable information for MFA treatment in premature infants with symptomatic patent ductus arteriosus and for preventing possible toxic effects. However, the excessive intake of MFA leads to diarrhoea, vomiting, lactic acidosis, hepatic necrosis, liver injury, morbidity and mortality in humans. Consequently, the development of an inexpensive, sensitive and accurate analytical method for determination of MFA is of considerable importance.

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed agents worldwide due to their anti-inflammatory, antipyretic and analgesic properties and are usually used in the treatment of inflammatory and degenerative diseases of the articulations. In addition, epidemiological studies have shown that long-term use of NSAIDs reduces the risk of developing Alzheimer disease and delays its onset. This category of drugs alleviate pain by counteracting the cyclooxygenase (COX) enzyme. On its own, COX enzyme synthesizes prostaglandins, creating inflammation. In whole, the NSAIDs prevent the prostaglandins from ever being synthesized, which otherwise lead to an increase of vascular permeability, edema, hyperalgesia, pyrexia, and inflammation. These drugs have also shown to induce various forms of adverse drug reactions, including adverse gastrointestinal effects, renal dysfunction and nephrotoxicity, liver damage, adverse neurological effects, and rhabdomyolysis.

Herein, we report the selective and sensitive determination of mefenamic acid on single walled carbon nanotubes modified glassy carbon electrode (GCE) employing square wave voltammetry. The developed sensor exhibited amelioration in the peak current response with a negative shift in the peak potential in comparison to multi walled carbon nanotubes modified GCE and bare GCE. Voltammetric studies indicated the oxidation of MFA at the electrode surface through a one electron and one proton irreversible step and fundamentally controlled by adsorption. A good linear relationship has been found between the anodic peak current and mefenamic acid concentration in the range of 0.1 – 35 µM with limits of quantification and detection as 44.7 and 13.4 nM, respectively. The interfering effect of physiologically common interferents on the current response of mefenamic acid has been reported. Furthermore, the proposed method was successfully applied to the determination of mefenamic acid in pharmaceutical formulations and human plasma samples.