ABSTRACT:
Four different selective, sensitive, precise and accurate UV spectrophotometric methods were developed and validated for simultaneous determination of binary mixture of sulphadoxine (SDX) and trimethoprim (TRM) in a veterinary pharmaceutical dosage form. The First method is the dual wavelength (DW-SM), which is based on measuring the difference in absorbance at two selected wavelengths (?A274.2 nm-299.5 nm) for determination of SDX and (?A238.1 nm-300.1 nm) for determination of TRM where the component of interest has a notable difference in absorbance and the other component shows zero absorbance at the same selected wavelengths, The second method is based on using derivative spectrophotometry. The first derivative spectrophotometric method (1D) was adapted for selective determination of SDX and TRM by measuring the peak amplitude at 289.2 nm and 230.5 nm, respectively. The third method is ratio difference spectrophotometric method (RD-SM) which is based on measuring the difference in peak amplitude of the ratio spectra at (?P260.7nm-229.5nm) for determination of SDX and (?P233.6nm-247.6nm) for determination of TRM. The fourth method depends on measuring the peak amplitude of the first derivative of ratio spectra (1DD) at 254.4 nm and 224 nm for determination of SDX and TRM, respectively. The proposed spectrophotometric methods were validated according to the ICH guidelines and applied successfully for simultaneous quantitative analysis for both drugs in pure form, laboratory prepared mixture and in their combined veterinary pharmaceutical dosage form. Statistical comparison was done between the obtained results and those obtained by the reported method, showing no significant difference with respect to accuracy and precision at p = 0.05.