Desenvolvimento de métodos eletroforéticos e cromatográficos para a determinação de benzodiazepínicos como adulterantes em formulações fitoterápicas para emagrecimento

Abstract

The adulteration of phytotherapic formulations has been increasing considerably in the recent years in several countries, by the fact that there is not an established efficient monitoring for the control of the manipulation and commercialization of the so called natural medicines . As the possibility of adulteration is relatively wide in terms of compound classes, the need of analytical methods with good sensitivity and selectivity, which are able to identify and quantify simultaneously more than one pharmaceutical in the same phytotherapic formulation, is very important. Considering the well known effects of these adulterants and its use and abuse in the formulations for weigh loss, two separations methods were developed in this study to enable the study of benzodiazepines alprazolam, clonazepam, chlordiazepoxide, diazepam, flurazepam, lorazepam, medazepam and midazolam as possible adulterants in phytotherapic formulations. For the electrophoretic method the optimized conditions were: buffer phosphate 100 mM, 15% acetonitrile (pH 2,0) as an electrolyte; fused silica capillary coated with a 60 cm layer of polymida (9,5 cm to the detector window) with 75 Um of internal diameter, operating at 25 °C; 15 kV of applied voltage, UV detection at 200 nm and anodic hydrodynamic injection for 2 seconds with a pressure of 30 mbar. The chromatographic method was optimized as the following conditions: eluent acetonitrile: water 40:60 (v / v) (pH 4,0) at flow 0,5 mL/min, UV detection at 230 nm and injection of 20 μL. The adulteration in these phytotherapic formulations occurs usually with the use of only one pharmaceutical class: a benzodiazepine, a anorexic and a antidepressant. It is not expected to find in the same sample more than one benzodiazepine. Therefore, the eletroforetic and chromatography proposed methods do not have the objective to detect all of benzodiazepines together in a same sample, but rather to promote the individual identification of all in a sample. The RP-HPLC method was validated for the determination of these benzodiazepines and applied for the determination of the adulterants in phytotherapic formulations used in the treatment of obesity, which have been commercialized as natural medicines by Brazilian pharmacies. The recovery experiments promoted recoveries values higher than 84,25 % for all the analyzed adulterants. The developed methods introduced high sensitivity, analytical precision, low cost and rapid analysis, confirming the applicability of the methods as an alternative for the control and monitoring of abuse use of these pharmaceuticals in phytotherapic formulations passible of adulteration.