Application of New Spectrofluorometric Techniques for Determination of Atorvastatin and Ezetimibe in Combined Tablet Dosage Form

Two accurate, reliable, and highly sensitive spectrofluorometric methods were developed for simultaneous determination of the binary mixture of Atorvastatin and Ezetimibe without prior separation steps. The first method is based on double scan synchronous fluorescence spectrometry. Each of Atorvastatin and Ezetimibe can be determined independent of the other when scanned at Delta lambda=100 urn and 40nm, respectively. The relative fluorescence intensity-concentration plots at two wavelengths, 272 (Delta lambda=100nm) and 266nm (Delta lambda=40nm) were rectilinear over the range of 0.4-8 mu g/mL (for Atorvastatin) and 0.6-8, mu g/mL (for Ezetimibe), respectively. The second method is based on the technique of simultaneous equations (Vierodt's method), in which two equations are solved simultaneously after using a single excitation wavelength of 273 nm and lambda(Em1)=380 nm of Atorvastatin and lambda(Em2)=301 nm of Ezetimibe. Under the optimum conditions, linear relationships were found between the relative fluorescence intensity and the concentrations of the investigated drugs in the range of 0.4-8 mu g/mL (for Atorvastatin) 0.6-8 mu g/mL (for Ezetimibe). The different experimental parameters affecting the fluorescence intensities of the two drugs were carefully studied and optimized. The proposed methods were successfully applied for the determination of the investigated drugs in pure form, dosage form and in synthetic mixtures with good recovery and the results obtained were favorably compared to those obtained with a reference method.