Journal of Applied Chemical Science International

Repaglinide (RPG) is an antidiabetic drug used in the treatment of type 2 diabetes. One titrimetric and two spectrophotometric methods for the determination of RPG in bulk drug and tablets are proposed. Drug solution in anhydrous acetic acid is titrated with acetous perchloric acid to a crystal violet end-point in titrimetry (titrimetric method). In spectrophotometry, intensely coloured ion-pair complexes, formed on interacting RPG with bromocresol purple (BCP) (SP-BCP method) and bromocresol green (BCG) (SP-BCG method) in dichloromethane medium, are measured at 400 and 425 nm, respectively. Different experimental parameters affecting the assays were carefully studied and incorporated in to the procedures. RPG was found to react with perchloric acid in a 1:1 ratio, and this served as the basis for calculations in titrimetry, which is applicable over 1-10 mg range. Under the described conditions, spectrophotometric methods obeyed Beer’s law in the range: 1-16 µg/mL for both the methods with molar absorptivity values of 1.16 × 10³ and 1.57 × 10³ L/mol/cm with BCP and BCG, respectively. The limits of detection (LOD) and quantification (LOQ) were calculated to be 1.94 and 5.85 µg/mL for BCP method and 0.95 and 2.85 for BCG method. From Job’s method of continuous variations, the drug-reagent reaction was found to follow a 1:1 stoichiometry. Intra-day and inter-day %RSD values were ≤2.02 and the corresponding %RE values were better than 2.33. The developed methods were applied to the determination of RPG in tablets and the results were satisfactory with an error of <2%. Accuracy was also examined by performing recovery study via standard-addition procedure, and the methods were found to be free from interference from co-formulated substances.