Comparison of the Conventional Methods and High-Performance Liquid Chromatography for the Determination of Trimethoprim, Sulfamethoxazole and Its Metabolite in Serum

Abstract

A modified high-performance liquid chromatographic (HPLC) method for sensitive and rapid determination of trimethoprim, sulfamethoxazole and its metabolite N₄-acetylsulfamethoxazole has been compared with the bioassay for trimethoprim and a colorimetric procedure for sulfonamides. The sensitivity of the (HPLC) method has been increased by ultrafiltration of the sample. Thus, the sample dilution was markedly reduced compared to the values obtained with precipitation procedures. The recovery was 102.7 ± 6.1% for trimethoprim, 93 ± 5.4% for sulfamethoxazole and 90.2 ± 7.9% for N₄-acetylsulfamethoxazole. The between-day reproducibility was 5% (n = 5). The coefficients of correlation for HPLC and reference methods were 0.993 (bioassay) and 0.995 (colorimetic assay).

The comparison of some pharmacokinetic parameters of sulphadimethoxine estimated by high performance liquid chromatography and three spectrophotometric methods

“…The differences observed in sulphonamide pharmacokinetics in individual human subjects were therefore not due to the method of the assay used. Not only did individual concentration values show good compatibility, as can be seen either from separate maximal concentration assayed by different methods or the reported findings of other studies (9), but also the pharmacokinetic parameters calculated from the determined levels did not differ significantly. Although the most objective of the examined techniques -high performance liquid chromatography -allows specific determination of the unchanged drug, the cheaper spectrophotometric techniques based on Bratton -Marshall or Morris reactions furnish comparable results.…”

“…Most frequently used for routine analysis are spectrophotometric techniques based upon BrattonMarshall reaction and chromatographic methods, particularly HPLC. To my knowledge, there have been only a few studies in which the individual concentrations of sulphonamides assayed by different methods were compared (2,9), but none with the goal of determining whether different methods of evaluating a drug could alter its pharmacokinetic parameters.…”