Discrete Wavelet Transform-Partial Least Squares Versus Derivative Ratio Spectrophotometry for Simultaneous Determination of Chlorpheniramine Maleate and Dexamethasone in the Presence of Parabens in Pharmaceutical Dosage Form

Purpose: To compare two methods, based on different approaches, for simultaneous determination of chlorpheniramine maleate (CHP) and dexamethasone (DX) in the presence of methyl and propyl paraben in phenadone syrup.
Methods: The first method used, based on univariate calibration approach, was first derivative of the ratio spectrophotometry (DD1). The second method, which is a multivariate calibration approach, was discrete wavelet transform followed by partial least squares method (DWT-PLS) which anticipated high predictive ability for the determination of both CHP and DX.
Results: DD1 method failed to determine DX due to the absence of adequate zero crossing point while DWT-PLS method was successfully applied for the analysis of raw materials and the dosage form. For DD1 method, recovery of chlorpheniramine maleate in the dosage form was 100.33 ± 0.91 % while for DWT-PLS method, recovery of chlorpheniramine maleate and dexamethasone was 100.24 ± 1.21 and 99.99 ± 1.08 %, respectively. The proposed methods were validated using standard addition technique and the results compared favorably with those obtained by a reference high performance liquid chromatography (HPLC) method.
Conclusion: The findings of this work show the superiority of DWT-PLS over DD1 method in solving such complex mixtures, and would thus be suitable for use in quality control (QC) laboratories and pharmaceutical industry.

Keywords
Quantitative analysis; Discrete wavelet transform; First derivative of ratio spectra; Chlorpheniramine maleate; Dexamethasone