No abstract

In the present study, two sensitive, precise and accurate spectrophotometric methods have been developed for the determination of milnacipran in bulk and capsule formulation. The first method is based on the reaction of milnacipran with ninhydrin in N,N'-dimethylformamide medium at 80°C temperature to form a colored Ruhemann's purple, which exhibits absorption maximum at 575nm. The second method is based on extraction of milnacipran into chloroform as ion-pair with bromothymol blue. The yellow colored ion-pair complex exhibits absorption maximum at 410nm. Beer's law is obeyed in the concentration ranges 2.5-37.5μg/mL and 2-12μg/mL of milnacipran for methods I and II, respectively. The effect of experimental variables were investigated and optimized. The validation parameters like linearity, sensitivity, accuracy, precision and robustness were checked by following the ICH guidelines. The proposed methods were applied for the analysis of milnacipran in capsule formulation with good results.

Four sensitive, precise and accurate spectrophotometric methods for the estimation of solifenacin succinate (SFS) have been developed. Method A describes the interaction of SFS with potassium permanganate in alkaline medium to give green colored manganate ion with absorption maxima at 610 nm. Methods B and C are based on the formation of ternary complexes of SFS with, copper (II)/eosin (method B) and ammonium molybdate/ammonium thiocyanate (method C), respectively which are extracted into chloroform and have absorption maxima at 545 nm (method B) and 465 nm (method C). Method D was based on the formation of yellow colored ion-pair complex between bromocresol green and SFS in dichloromethane medium with absorption maxima at 415 nm. Regression analysis of Beer's law plot showed good correlation in the concentration range of 5-50, 2.5-50, 10-100 and 2-20 μg/mL for methods A, B, C and D, respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully for the analysis of SFS in tablets dosage forms. No interference was observed from common pharmaceutical excipients.

Two simple and sensitive visible spectrophotometric methods (I and II) are developed for the quantification of modafinil in pure and in tablet formulations. The methods (I and II) are based on the bromination of modafinil by a bromate/bromide mixture of known concentration in acid medium. The determination of residual bromine is based on its ability to bleach methyl orange (method I) and methylene blue (method II) and measuring the absorbance at 525 nm and 664 nm, respectively. In both methods, the amount of bromine reacted with the dye corresponds to the drug content. The different experimental parameters affecting the reaction and stability of the colored product are carefully studied and optimized. Beer's law is obeyed in the concentration ranges of 0.5-5.0 and 0.75-4.5 μg mL-1 with regression coefficient of 0.9981 and 0.9995 for methods I and II, respectively. The limits of quantification (LOQ) were 0.0540 and 0.0536 μg mL-1 for methods I and II, respectively. After validation according to the guidelines of International Conference on Harmonization, the proposed methods were successfully applied to assay modafinil in its tablet formulations. The label claim percentages were 99.97 ± 0.896% and 99.98 ± 0.884% for the methods I and II, respectively. No interference was observed from common excipients found in pharmaceutical preparations.

A simple and sensitive stability indicating HPLC method is developed for the quantification of rivaroxaban in bulk and tablet dosage form. Chromatographic separation was achieved on an ACE-Ciano column (250 mm x 4.6 mm, 5 μm particle size). The mobile phase consists of 0.1M sodium acetate and methanol (60:40 v/v) and was delivered at a flow rate of 1 mL/min. A UV detector was used for the detection. The rivaroxaban was subjected to stress conditions for the assessment of the stability-indicating nature of the method. The method was validated as per ICH guidelines. The linearity is obtained in the range of 1-120 μg/mL. The limit of detection and quantification values is 0.194 μg/mL and 0.648 μg/mL respectively. The intra and inter-day %RSD values were below 1%. Intra and inter-day accuracies were within 100.10% and 100.40%, respectively. Degradation products resulting from the stress studies have no interfere with the detection of rivaroxaban. The average recovery of rivaroxaban in tablet dosage form was 99.74% with %RSD of 0.421%. The developed method was proved adequate for quantitative determination of rivaroxiban in presence of its degradation products.