Resumen Las herramientas de transformada continua de wavelets fueron empleadas para el procesamiento de espectros de absorción UV con el fin de lograr la cuantificación y la comprensión del comportamiento de fumarato de disoproxilo de tenofovir (TEN) y de emtricitabina (EMT) en la disolución in vitro de las tabletas comerciales, con bajo costo y corto tiempo de análisis. Se realizaron pruebas preliminares de análisis de señales para determinar la familia o familias de ondículas más adecuadas para monitorear los perfiles de disolución in vitro y para cuantificar los fármacos de interés. Entre ellos, las herramientas Daubechies (db6), Symlets 3 (sym3), Biorthogonal 1.5 (bior1.5) y Coiflets 5 (coif5) resultaron ser óptimas proporcionando resultados deseados. Funciones de calibración obtenidas mediante el análisis de regresión de señales de ondículas transformadas (variable dependiente) obtenidas para soluciones de calibración (concentración - variable independiente) presentaron buena linealidad en el intervalo de concentraciones 4.0-52.0 µg/mL para ambos fármacos. La validez de procesamiento de señales CWT fue demostrada mediante el análisis de mezclas de conocidas concentraciones, preparadas en el laboratorio. La cuantificación de TEN y EMT no requiere su separación previa. El procedimiento fue empleado en el ensayo de monitoreo de la disolución in vitro de los fármacos y en las tabletas con contenían los dos fármacos. En este trabajo se propone un procedimiento basado en CWT, alternativo respecto a la tradicional espectrofotometría de derivadas para resolución de mezclas binarias sin necesidad de separación previa de dos componentes.

Abstract Wavelet signal processing tools were applied to the UV spectral dataset for the quantification and understanding the in vitro dissolution behaviors of tenofovir disoproxil fumarate (TEN) and emtricitabine (EMT) in commercial tablets with low-cost and short analysis time. Preliminary signal analysis tests were staged to determine the most suitable wavelet family or families to monitor in vitro dissolution profiles and quantify the drugs of interest. Of these, Daubechies (db6), Symlets 3 (sym3), Biorthogonal 1.5 (bior1.5) and Coiflets 5 (coif5) continuous wavelet tools have been found to be optimal as they provide the desired results. Calibration curves obtained by regression analysis of the continuous wavelet signal (dependent variable) on concentration (independent variable) were found to be linear in the range of 4.0-52.0 µg/mL for both drugs. The validity of CWT signal processing tools was tested by analyzing mixtures made in the laboratory. The Quantitation of TEN and EMT by the proposed signal processing tools did not require a pre-separation procedure. They were successfully utilized for the assay and in vitro dissolution monitoring of the two drugs in their combined tablets. Consequently, the presented work provided alternative tools based on wavelet signal processing to traditional derivative spectrophotometry to resolve a two-component mixture without using a priori separation step.

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.