Development and Validation of Spectrophotometric and Spectrofluorimetric Methods for the Determination of Cyclobenzaprine HCl

Five simple and sensitive methods were developed for the determination of cyclobenzapirine hcl (CB) in presence of its degradation product anthraquinone (AQ). Method A dual wavelength spectrophotometry (DW); where two wavelengths were selected for the drug 283 and 306 nm in such a way that the difference in absorbance was zero for its degradation. Method B ratio difference spectrophotometry (RD) was depended on measuring the ratio difference between 290 and 305 nm. Method C was depended on measuring the peak amplitude of the first derivative of the ratio spectra (1DD) at 282 and 306 nm. Method D Isoabsorptive Point (ISO) at 280 nm Coupled with Second Derivative (2D). Method E depending on spectrofluorimetric determination of cyclobenzapirine HCl through quenching of uranyl acetate with ʎexi 228 nm and ʎem at 458 nm. Linearties were obtained in concentration range 5 μg/ml – 30 μg/ml in case of methods A, B, C and D, while in case of methods E linearity was obtained in concentration range of 1 μg/ml –10 μg/ml. The five methods were found to be specific for CB in presence of different concentration % of its degradation product. The five proposed methods were successfully applied for the determination of CB in Multirelax tablets. Statistical comparison between the results obtained by the proposed methods and that obtained by the official one for the determination of the drug was done, founding that there were no significant differences between them.