Abstract
This study describes the development and validation of a new 96-micorwell-based spectrophotometric assay with high-throughput for pharmaceutical quality control of lenalidomide (LND), the new drug for treatment of multiple myeloma. The reaction between LND and 1,2-naphthoquinone-4-sulphonate (NQS) as a chromogenic reagent was investigated. In alkaline medium (pH 9), a red-colored product exhibiting maximum absorption peak (lambda(max)) at 462 nm was produced. The stoichiometry and Idnetic of the reaction were investigated and the reaction mechanism was postulated. This color-developing reaction was employed, for the first time, in the development of the proposed assay. The reaction was carried out in 96-microwell plate and the absorbance of the colored-product was measured by microwell plate absorbance reader at 450 fun. The optimized reaction conditions were established; under which, Beer's law correlating the absorbance with LND concentration was obeyed in the range of 3-100 mu g/mL with appropriate correlation coefficient (0.9986). The limits of detection and quantification were 2.82 and 855 mu g/mL, respectively. The assay showed high precision as the values of relative standard deviations (RSD) did not exceed 125%. No interference was observed from the excipients that are present in the capsules. The proposed assay was applied successfully for the determination of LND in its pharmaceutical capsules with appropriate accuracy and precisions; the label claim percentage was 101.43 +/- 135%. The results were compared favorably with those of a reference pre-validated method. The proposed assay is practical and valuable in terms of its routine application in pharmaceutical quality control laboratories.