Simultaneous determination of the two non-steroidal anti-inflammatory drugs; Diflunisal and Naproxen in their tablets by chemometric spectrophotometry and HPLC

Chemometric spectrophotometry and HPLC were applied to the simultaneous determination of the two non-steroidal anti-inflammatory drugs; diflunisal [I] and naproxen [II]. The applied chemometric techniques are multivariate methods including classical least squares [CLS], principal component regression [PCR] and partial least squares [PLS]; and the second derivative of the ratio spectra [2Dr] method. To develop the multivariate methods, the UV absorption spectra of the standard solutions of the training and validation sets in methanol were recorded in the range of 242-274 nm at 2 nm intervals. The specificity of the studied multivariate methods has been tested. In the 2Dr method, analytical signals at 235 and 259 nm were selected for the determination of [I] and [II], respectively. The HPLC method depends on reversed-phase separation using C18 column. The mobile phase consists of a mixture of acetonitrile - acetate buffer [pH 4.2; 50 mM] [60:40, v/v]. The UV detector was set at 255 nm. The developed methods were validated and successfully applied to the simultaneous determination of [I] and [II] in their tablets. The assay results obtained using the chemometric methods were statistically compared to those of the HPLC method and good agreement was observed

Spectrofluorometric determination of the two antilipemic drugs lovastatin and simvastatin in spiked human plasma and in dosage forms

A new spectrofluorimetric method for the determination of the two antilipemic drugs, lovastatin and simvastatin, was described. The method is based on heating drug solution with 2-aminoethane sulfonic acid [taurine] 0.025% w/v solution in phosphate-borate buffer of pH 7.4 at 70C for 30 minutes. The resulting reaction product exhibits strong fluorescence at 388 nm after excitation at 318 nm. Different assay parameters have been optimized to achieve maximum sensitivity and reliability of the method for the determination of the 2 drugs in spiked human plasma as well as in their dosage forms. The intensity of the resulting fluorescence showed linear relation with concentrations of both drugs in the range of 0.2 to 0.8 mug/L. The mean percentage recoveries of lovastatin and simvastatin were 99.851 SD +/- 2.101 and 99.806 SD +/- 1.805, respectively, in case of six concentrations of human plasma. The limit of detection was found to be 0.2 mug/L. The method is recommended for drug monitoring in biological fluids. The method was successfully applied for the determination of lovastatin and simvastatin in dosage forms. The results were in agreement with those of some other reported methods