Simultaneous determination of pyrimethamine and mefloquine in human plasma by high-performance liquid chromatography with ultraviolet detection

Stereospecific determination of mefloquine in biological fluids by high-performance liquid chromatography

A sensitive stereoselective HPLC method was developed for determination of mefloquine (MFQ) enantiomers in plasma, urine and whole blood. The assay involved liquid-liquid extraction of MFQ from biological fluids with a mixture of hexane and isopropanol in the presence of sodium hydroxide and derivatization of the residue by (+)-(S)-naphthylethylisocyanate (NEIC) as chiral derivatizing reagent. Separation of the resulting diastereomers was performed on a silica normal-phase column using chloroform-hexane-methanol (25:74:1) as the mobile phase with a flow-rate of 1 ml/min. Using 200 microl of plasma or whole blood, the limit of determination was 0.2 microg/ml with UV detection for both enantiomers. The limit of determination in 500 microl of urine was 0.08 microg/ml with UV detection.

Improved column-switching liquid chromatographic method for the determination of the enantiomers of mefloquine

A liquid chromatographic method for the determination of the enantiomers of mefloquine has been improved. The chromatography involved two columns: an achiral cyanopropyl stationary phase for the quantification of (+/-)-mefloquine and a chiral naphthyl-urea stationary phase for the determination of the enantiomeric ratio. Compared with the previous method, which needed two detectors, this one used one detector-integrator to which the two columns are connected alternately by an automated column-switching system. The method is suitable for the quantification (0.05 microgram/ml) of mefloquine and the determination of enantiomeric ratios from 500-microliters plasma samples with ultraviolet detection.

Reversed-phase liquid chromatographic method for the simultaneous determination of the antimalarial drugs sulfadoxine, pyrimethamine, mefloquine and its major carboxylic metabolite in plasma

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of sulfadoxine, pyrimethamine, mefloquine and the carboxylic metabolite of mefloquine in plasma is described. After the proteins have been precipitated with a combination of zinc sulphate and acetonitrile containing two internal standards, pyrimethamine and mefloquine are extracted as bases and sulfadoxine and the carboxylic metabolite of mefloquine as ion-pairs with tetrabutylammonium. The drugs are separated by HPLC on a 3 micron octadecylsilica column with ultraviolet detection at 229 nm. The method is simple and reliable and enables the simultaneous determination of the drugs in 600-microliter plasma samples with a sensitivity suitable for standard drug monitoring purposes.