Spectrophotometric Determination and Validation of Glimepiride in Pure and Tablet Dosage Forms through Ion-pair Complex Formation Using

Objective: A simple, direct and accurate spectrophotometric method has been developed for the determination of glimepiride (GLM) in pure and pharmaceutical formulations by complex formation with bromocresol green (BCG). Methods: The method involves the formation of a yellow ion-pair complex between bromocresol green reagent with glimepiride (C24H34N4O5S); after reacted it with Na2CO3 to give C24H33N4H+O5NaS in chloroform at pH≤3.8. Results: The formed complex was measured at λmax 416 nm against the reagent blank prepared in the same manner. Variables were studied in order to optimize the reaction conditions. Beer’s law was obeyed in the concentration range of 0.981-9.812 μg/ml in the present of 1x10-4 mol/l of (BCG) and 9.812-58.874 μg/ml in the present of 1x10-3 mol/l of (BCG) with good correlation coefficient (R2= 0.9992 and R2= 0.9997, respectively). The relative standard deviation did not exceed 3.0%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.088 and 0.29 μg/ml, respectively. The proposed method was validated for specificity, linearity, precision and accuracy, repeatability, sensitivity (LOD and LOQ), and robustness with average recovers 98.9 to 102.4%. Conclusion: The developed method is applicable for the determination of glimepiride in pure and different dosage forms with average assay of marketed formulations 97.8 to 102.4% and the results are in good agreement with those obtained by the RP-HPLC reference method.