UTILIZATION OF ION-PAIR COMPLEX FORMATION FOR THE SPECTROPHOTOMETRIC DETERMINATION OF SOME ANTIDEPRESSANT DRUGS IN PHARMACEUTICAL FORMULATIONS

Objective: A new, simple and sensitive spectrophotometric method has been developed for the determination of some antidepressant drugs, namely desvenlafaxine (DSV), dapoxetine (DAP) and citalopram (CIT) in pharmaceutical formulations.Methods: The proposed method was based on the formation of yellow colored ion-pair complex between the studied drugs and two sulphonphthalein dyes viz., bromophenol blue (BPB), and bromothymol blue (BTB) in acidic medium. The optimizations of the reaction conditions were investigated. Beer's law limits, Sandell's sensitivity, correlation coefficient, detection, and quantification limits were calculated.Results: The formed complexes showed absorption maxima at 412 nm and 410 nm measured for all the drugs with BPB and BTB, respectively. The Job's method of continuous variations indicated that a single l: l ion-pair complex was formed. Calibration curves were linear over the concentration range of 0.8–11.4, 0.8–6.4 and 0.8–8.0 μg/ml for DSV, DAP and CIT, respectively.Conclusion: The proposed method has been applied successfully for the analysis of the investigated drugs in pure and in their dosage forms. No interference was observed from common excipients present in pharmaceutical formulations. The proposed method is suitable for quality control applications.Keywords: Desvenlafaxine, Dapoxetine, Citalopram, Sulphonphthalein dyes, Extraction spectrophotometry, Pharmaceutical formulation

Kinetic spectrophotometric method for the determination of some fourth generation fluoroquinolones in bulk and in pharmaceutical formulations

A kinetic spectrophotometric method for accurate and sensitive determination of gemifloxacin (GMFX) and gatifloxacin (GTFX) has been described. The method is based on the reaction of the studied drugs with potassium permanganate in the presence of sodium hydroxide to form a water-soluble green product which shows maximum absorbance at 604 nm. The determination of GMFX and GTFX drugs by rate constant, fixed-concentration, and fixed time methods was feasible with the calibration equations obtained but the fixed time method had been found to be more applicable. The concentration of the selected drugs is calculated using the calibration equation for the fixed time method. The absorbance–concentration plot is linear over the range of 4–36 μg mL−1 and 4–40 μg mL−1 with correlation coefficient of 0.9998 and 0.9991, for GMFX and GTFX, respectively. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The intra- and inter-day RSD values indicated the ruggedness of the method. The proposed method has been successfully applied to pharmaceutical formulations of each drug. Statistical comparison of the results with a well established reported method showed excellent agreement and proved that there is no significant difference in the accuracy and precision