Determinação de fármacos sintéticos em formulações farmacêuticas empregando métodos eletroquímicos e de separação

Abstract

The adulteration of natural pharmaceutical formulations using synthetic drugs has increased in the last years.Adulterations have been reported in the literature, which proves the increasing concern regarding this issue, and thus raising the development of analytic methodologies that are able to detect adulterations. This study describes the development of three methodologies for the determination of five synthetic drugs classes (anorexics, antidepressants, anxiolytics, diuretic, and laxatives) in natural formulations.Two methods were developed for screening samples using voltammetry of immobilized microparticles (VIM), and cathodic stripping voltammetry (AdCSV). Another method wasdeveloped for the separation and identification of 16 drugs of 5 different classes - anorexics (amfepramone, sibutramine, and femproporex), antidepressants (bupropion, fluoxetine, paroxetine, and sertraline), anxiolytics (alprazolam, bromazepam, flurazepam, lorazepam, chlordiazepoxide, diazepam, midazolam, and clonazepam), diuretic (furosemide), and laxatives (phenolphthalein and bisacodyl) - using ion-pair chromatography (IPC). The optimized conditions for the separation were as follows, eluent: tetrahydrofuran/acetronitrile/water (5/10/85) with 0.14 mol L-1 of dodecyl sodium sulfate, in pH 4, initial flow of 1.2 mL min-1, using a C18 column. The eluent s concentration and flow varied during the application of the gradient. The IMV method was applied in the screening of 49 pharmaceutical formulation samples, and 15 presented adulterations with anorectic, anxiolytic, and diuretic drugs. The CSV method was used in the screening of 99 samples, and 5 presented adulterations with anxiolytic and laxative drugs. The separation method was applied in 18 samples, and 3 presented adulterations with phenolphthalein (laxative).Both screening methods developed here were efficient in tracking samples, presenting advantages, such as speed and low reagent consumption. The separation method was validated according to linearity, detection limit, quantification limit, selectivity, precision, and analytic accuracy. Therefore, this method can be used to determine the adulterations presented here in natural pharmaceutical formulations.