Simultaneous kinetic-spectrophotometric determination of mycophenolate mofetil and mycophenolic acid based on complexation with Fe(III) using MCR-ALS

Determination of pharmaceutical analytes has been subjected to many investigations especially in transplantations in which accurate and precise detection of drugs is of importance. Mycophenolate mofetil (MPM) is a pro-drug that undergoes ester hydrolysis in liver and is converted to its active metabolite Mycophenolic acid (MPA) which inhibits purine biosynthesis and is responsible for pharmaceutical effects. Using this drug instead of MPA is because of higher safety and efficacy and lower costs of treatment. It has been shown that the lower concentrations of MPA in plasma correlate significantly with the risk of rejection while its high values increase the risk of toxicity in consumer patients so development of a simple and reliable method for fast and precise determination of MPM and MPA in pharmaceutical samples is of importance and a wide variety of analytical methodologies have been used for their determination [1- 4]. In this study, a simple and fast complexation reaction has been employed for simultaneous kinetic-spectrophotometric determination of these two immunosuppressant drugs which is based on the reaction between drugs and Fe(III) ions in the presence of sodium dodecyl sulfate as anionic surfactant by standard addition method. The effect of influential parameters including type of surfactant, concentration of Fe(III) ions and pH of the solution on complexation reaction have been studied and SDS was chosen as suitable surfactant while reaction proceeds with 0.1M Fe(III) at pH=4. Multivariate curve resolution-alternating least squares (MCR-ALS) has been employed for analyzing the multiset data obtained from augmentation of resulting standard addition matrices. Values for limit of detection (LOD) of method have been calculated as 2.1 μg. mL-1 and 5.8 μg. mL-1 for mycophenolic acid and mycophenolate mofetil respectively and Beer’s law is obeyed over the concentration ranges 10-250 μg. mL-1 for both analytes. The proposed method was successfully applied for determination of drugs in plasma serum samples and the accuracy and reliability of the method was further ascertained by recovery experiments via standard addition procedure.