Continuous wavelet transform methods for the simultaneous determinations and dissolution profiles of valsartan and hydrochlorothiazide in tablets

Erdal Dinç,Günseli Yüksel Tilkan,Nurten Özdemir,Berna Türkmen,Özgür Üstündağ

doi:10.1590/s2175-97902017000116050

Erdal Dinç, Günseli Yüksel Tilkan + Show 3 more

Open Access

https://doi.org/10.1590/s2175-97902017000116050

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Abstract

Continuous wavelet transform (CWT) was proposed for the simultaneous determination and dissolution profiles of valsartan (VAL) and hydrochlorothiazide (HCT) in tablets, without the use of a chemical separation procedure. The CWT approach was applied to the original UV spectra and their ratio spectra in the optimal wavelength ranges. After testing several wavelet families, Mexican hat function-CWT and Daubechies7-CWT (mexh-CWT and db7-CWT, respectively) were found to be suitable for the transformation of the original UV spectra. In the following procedure, mexh-CWT and Coiflets3-CWT (coif3-CWT) were found to be appropriate for the signal analysis of ratio spectra (RS) of VAL/HCT and HCT/VAL. Calibration graphs for VAL and HCT were obtained by measuring db7-CWT and mexh-CWT amplitudes in the transformation of the original absorption spectra and RS-coif-CWT and RS-mexh-CWT amplitudes in the transformation of the ratio spectra. The validity and applicability of the proposed CWT methods were evaluated through the analysis of an independent set of synthetic binary mixtures consisting of VAL and HCT. The proposed signal processing methods were then successfully applied to the simultaneous quantitative evaluation and simultaneous dissolution profiles of the related drugs in commercial tablets, with good agreement reported for the experimental results.

Highlights

The simultaneous analysis and simultaneous dissolution testing of combined pharmaceutical formulations are key issues in contemporary analytical chemistry and pharmaceutical technology due to the interference of the spectral bands within the same region, or due to unresolved chromatographic peaks of compounds that have similar chemical and physical properties
The overlapping absorption spectra of VAL and HCT compounds and their tablet sample are depicted in Figure 1, which demonstrates that conventional spectrophotometric approaches do not allow for the simultaneous quantitative analysis and simultaneous dissolution tests of VAL and HCT in their tablets
It is widely recognised that the simultaneous analysis and dissolution of multicomponent pharmaceutical preparation is a highly significant issue in analytical chemistry and pharmaceutical technology

Summary

Introduction

The simultaneous analysis and simultaneous dissolution testing of combined pharmaceutical formulations are key issues in contemporary analytical chemistry and pharmaceutical technology due to the interference of the spectral bands within the same region, or due to unresolved chromatographic peaks of compounds that have similar chemical and physical properties. The aforementioned problems have been solved through the use of several analytical techniques such as derivative spectrophotometry and high performance liquid chromatography (HPLC). A classical derivative technique – or its modified version – may not yield successful outcomes due to the presence of overlapping spectral bands, the interference. The WT approach is categorised into two classes: discrete wavelets transform (DWT) and continuous wavelets transform (CWT). CWT has often been used for the elimination of the noise effect, Braz.

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