Analytical method validation for determination of tuberculostatics in fixed dose combination by capillary electrophoresis

Abstract

The World Health Organization (WHO) has proposed a standard therapeutic protocol for tuberculosis utilizing combinations of drugs formulated in fixed and appropriated doses according to the phases of the disease and weight range of patients. This guidance aimed to reduce the occurrence of new cases and to minimize the development of resistance to the drugs involved in this therapy. In these combinations, isoniazid and rifampicin are always present. At the same time, to fight such a disease like tuberculosis, which is funded by the Brazilian public health system, the availability of analytic methods that are reliable, fast, low cost and less polluting, compared to liquid chromatography (HPLC), shows to be extremely important to the public budget, particularly in Brazil, that has achieved the sixth position in the world´s drug consumer´s market. Capillary Electrophoresis (CE) is an analytical tool that has been rapidly growing in the last two decades for being a technique of high performance and low cost requiring low volume samples and little or no use of organic solvents further on low environmental impact. This work was carried out a method validation for the analysis of isoniazid and rifampicin in tablets of Fixed Dose Combination (FDC) by CE. The used analytical method proved to be useful for quantitative determination of isoniazid and rifampicin in FDC tablets. It was proved that the working range is linear for the concentration interval of 200 to 700 µg/mL and 500 to 1000 µg/mL for isoniazid and rifampicin, respectively. The matrix of DFC 2 in 1 tablet does not interfere in the results for the analysis of isoniazid and rifampicin (no matrix effect). Method repeatabilities for rifampicin and isoniazid of 3.17 % and 2.64 %, respectively, were acceptable when compared by the acceptance criterion of 3.30 % for variation coefficient of repeatability calculated by Horwitz equation. Intermediate precisions of isoniazid and rifampicin of 1.41 % and 1.67 %, respectively, were acceptable when compared to the variation coefficients of reproducibility of 1.97 % and 1.67 % for isoniazid and rifampicin, respectively, calculated by Horwitz equation. Recuperation of 95.00 % for isoniazid and 97.59 % for rifampicin were acceptable for the criteria of acceptance of the European Community of 80 to 110 % for the concentration studied.