Abstract
Fluorescence spectra of FLD (1μgml−1) in; (a, b) 0.3% v/v Tween-80 system and (a′, b′) aqueous system, where: (a, a′) are the excitation spectra and (b, b′) are the emission spectra. [Display omitted]
•Sensitive spectrofluorimetric methods for determination of Felodipine & Nimodipine.•The first method is based on measuring the native fluorescence of cited drugs.•The second method depends on using Tween 80 as surfactant fluorescence enhancer.•Validation of the proposed methods according to the ICH guidelines.•Application of the proposed methods on different dosage forms & spiked human plasma.
Rapid, simple and sensitive two spectrofluorimetric methods have been developed for determination of Felodipine (FLD) and Nimodipine (NDP). The first method is based on measuring the native fluorescence of either Felodipine or Nimodipine at 426nm after excitation at 385nm. The fluorescence intensity-concentration plots of Felodipine and Nimodipine were rectilinear over the concentration ranges (0.2–3.0) and (0.5–4.0) μgml−1, respectively. The second method is based on measuring the fluorescence intensity of the studied drugs in micellar media (0.3% Tween-80) at λex=385nm and λem=423nm. In the presence of 0.3% Tween-80, about 1.6-fold and 2.1-fold enhancement can be achieved in the relative fluorescence intensity (RFI) of Felodipine and Nimodipine, respectively. The fluorescence intensity-concentration plots of Felodipine and Nimodipine with Tween-80 were rectilinear over the concentration ranges (0.05–4.0) and (0.1–4.0) μgml−1, respectively with determination coefficients (r2) of 0.9981 and 0.9990, and limit of quantitation of 0.05 and 0.027μgml−1 for FLD and NDP, respectively. The proposed methods were validated according to ICH guidelines and have been successfully applied to the analysis of these drugs in their commercial tablets with high accuracy (97.6–98.8±0.50–1.42%, n=5). The high sensitivity of micellar method permits its application for determination of the cited drugs in spiked human plasma with % recovery (91.9–106.6±0.66–1.7%, n=6).