Investigation of Chromatographic Behavior of Leflunomide and its Identification in Pharmaceutical Dosage form by Reversed Phase Liquid Chromatography

• Published in: Journal of liquid chromatography & related technologies Vol. 38; no. 1; pp. 97 - 103
• Main Authors: Yilmaz, Hülya, Çubuk Demiralay, Ebru
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 02.01.2015; Taylor & Francis Ltd
• Subjects: Chromatography; Constants; dissociation constant; Dosage; leflunomide; Liquid chromatography; Liquids; Mathematical analysis; method validation; pharmaceutical dosage form; Pharmaceuticals; RPLC; U.S. Pharmacopeia
• ISSN: 1082-6076; 1520-572X
• DOI: 10.1080/10826076.2014.883537

Dissociation constant value ( ) is key parameter for predicting the extent of the ionization of a drug molecule at different pH. In this study, pK a values of leflunomide in different percentages of acetonitrile-water binary mixtures (50%, 55%, and 60%, v/v) were determined from the mobile phase pH dependence of retention factor with reverse phase liquid chromatographic method (RPLC). From calculated pK a values, the aqueous pK a value of leflunomide was calculated by various approaches. Moreover, the correlation established between retention factor and the pH of the water-acetonitrile mobile phase was used to determination of optimum separation condition. In order to validate the optimized condition, leflunomide was studied in pharmaceutical dosage form. A Gemini NX C18 column (250 × 4.6 mm I.D., 5 µm particles) was preferred to carry out the developed method. The parameters, linearity, precision, accuracy, specificity, limit of detection, and limit of quantitation were studied according to U.S. Pharmacopeia.