A new spectrofluorimetric assay method for vandetanib in tablets, plasma and urine

Purpose: To develop a simple and sensitive spectrofluorimetric method for the determination of vandetanib (VDB) in tablets (containing 100 mg of the drug) and biological fluids (spiked human plasma and urine).
Methods: The proposed method is based on examining the intrinsic fluorescence intensity of VDB in acetonitrile at 480 nm after excitation at 330 nm. Factors affecting fluorescence intensity of the cited drug (VDB), including the influence of pH, diluting solvent and time, were studied and optimized by one factor at a time approach. A calibration curve was constructed by plotting VDB fluorescence intensity at 480 nm versus VDB concentrations in ng mL^-1. The method was validated according to the recommendations of International Conference on Harmonisation (ICH) for validation of the analytical procedures
Results: The linearity range of the method was 20 – 600 ng mL^-1, with limits of quantification (LOQ) and of detection (LOD) of 30.45 and 10.05 ng mL^-1, respectively. The adopted method was applied successfully to the quantitation of VDB in pure powder form (100.90 ± 0.91 %), laboratory prepared tablets (97.86 ± 1.42 %), spiked human plasma (97.97 ± 2.36 %) and urine (97.59 ± 0.87 %). Comparison of the proposed method with that of liquid chromatography-tandem mass spectrometry showed that there was no significant difference (p < 0.05) between the two methods in terms of accuracy and precision.
Conclusion: The proposed method is simple and highly sensitive and, consequently, can be applied to assay VDB in biological samples as well as in dosage form.

Keywords
Vandetanib; Spectrofluorimetry; Assay; Validation; Human plasma; Human urine; Dosage forms