Micellar Matrices for Spectrophotometric Determination of 5-Aminosalicylic Acid in Medicinal Preparations Using Response Surface Methodology and Box-Benken Plans

Abstract

Determination of the content of insoluble pharmaceutical substances in dosage forms is an urgent task, since their dosage is very important for the optimal ratio between the therapeutic effect and ensuring the necessary bioavailability. The use of micellar media as a matrix allows increasing solubility. This report presents the results of the influence of the micellar system consist from cetyltrimethylammonium bromide, CTAB, dimethyl sulfoxide, DMSO and water on the determination of the content of 5-aminosalicylic acid (5-ASA) in pharmaceutical substances and in dosage forms. 5-ASA is widely used for the treatment of inflammatory bowel diseases, ulcerative colitis and Crohn's disease. To obtain the optimal matrix, the methodology of the response surface (MRS) and three-level Box-Benken plans (BBP) were used. The intensity of the absorption band of 5-ASA (A330), which reflects the acid content, was used as the target function. The independent factors were: the concentration of CTAB (pC(CTAB), mol/l); the acidity of medium (pH); the proportion of DMSO in the binary solvent (αDMSO). The BBP consisting of fifteen compositions were compiled and response surfaces constructed. Optimal conditions for the determination of 5-ASA by the absorption band A330 are: pC(CTAB) = 1.1, pH = 7.6, α(DMSO) = 0.3. In this matrix, the content of 5-ASA in the pharmaceutical substance was established and good metrological performance was achieved. The use of MRS and BBP contributes to the development of effective methods for quality control of 5-ASA dosage forms from different manufacturers.