Blokatens tablets are novel prescription drug that combines amlodipine besylate (AM) with valsartan (VS), were simultaneously determined by two different spectrofluorimetric methods. The first method depend on measurement of native fluorescence intensity of both drugs at ג emission 460nm and 385 nm using ג excitation 390nm and 227nm for AM and VS respectively in water. The second method utilizes synchronous fluorimetric quantitative screening of the emission spectra of AM and VS at 375 and 285 nm, respectively using Δλ of 80 nm. The different experimental parameters affecting the synchronous fluorescence intensity of two drugs were carefully studied and optimized. The method was validated according to ICH guidelines. Linearity, accuracy and precision were found to be satisfactory in both methods over the concentration ranges of 0.4-14 and 1.0-22µg/mL for AM and VS, respectively. In the first method, limit of detection and limit of quantification were estimated and found to be 0.165 and 0.5µg/mL for AM as well as 0.495 and 1.5 µg/mL for VS, respectively. Also, limit of detection and limit of quantification were calculated in the synchronous method and found to be 0.148 and 0.45 µg/mL for AM as well as 0.396 and 1.2 µg/mL for VS, respectively.Excellent linearity was observed,careful validation proved advantages of the new methods: high sensitivity, accuracy, selectivity and suitability for quality control laboratories. The results were compared statistically with reference methods and no significant difference was found. The methods were successfully applied for the determination of the two drugs in their co-formulated tablets without pre-separation.
