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Journal of Chromatography, 494 (1989) 219-230 BlomedLcal Applxattons Elsevler Science Pubhshers B V , Amsterdam - Prmted m The Netherlands

CHROMBIO 4859

SIMULTANEOUS DETERMINATION OF PYRIMETHAMINE AND MEFLOQUINE IN HUMAN PLASMA BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION

A GUENZI*, G CAPPELLETTI, A SCALA and M ZANETTI

PharmacokuxetLcs Laboratoory, Prodottl Roche SPA, Piazza Durante 11,20131 Milan (Ztaly)

(First received February 21st, 1989, revised manuscript received May 3rd, 1989)

SUMMARY

A rapld, sensltlve and selectlve method was developed for the simultaneous determination of pyrlmethamme and mefloqume, two of the active mgredlents of FanslmefQ, m human plasma The procedure involved extra&on of the compounds and the internal standard mtrazepam from baslfied plasma with dlchloromethane and chromatography on a C,, column (PBondapak, 300 x 3 9 mm I D ) with acetonltrlle-phosphate buffer as the mobile phase and UV detection at 222 nm The hmlt of quantlficatlon was 10 ng/ml for both substances, usmg a l-ml plasma specimen The mean mter-assay preclslon was 2 8% for pyrlmethamme and 4 7% for mefloqume up to 800 ng/ ml The practlcablhty of the method was demonstrated by the analysis of more than 1200 plasma samples from several pharmacokmetlc studies mvolvmg smgle-dose admuustratlon of Fanslmef to both patients and volunteers

INTRODUCTION

Fanslmef@ (Hoffmann-La Roche, Basle, Switzerland) 1s an antlmalarlal drug conslstmg of a fixed combmatlon (1 10 20, w/w/w) of pyrlmethamme (I ), mefloqume (II) and sulphadoxme (III) (Fig 1) The three active mgredlents act on protozoa of the PhmodLum genus by different mechamsms pyrlmeth- amine, a 2,4-dlammopyrlmldme, 1s a dlhydrofolate reductase mhlbltor [ 11, sulphadoxme, a sulphonamlde, 1s a dlhydropteroate synthetase mhlbltor [2] and mefloqume, a qumohnemethanol, appears to affect membranes of malarial parasites [ 31 Pyrlmethamme and sulphadoxme act synerglstlcally and meflo- qume further enhances their effect Fanslmef was formulated with the aim of

O378-4347/89/$03 50 0 1989 Elsevler Science Publishers B V

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Fig 7 Plasma concentration-time course of II followmg a smgle oral dose of one tablet of Fanslmef (25 mg of I, 250 mg of II, 500 mg of III) to a healthy volunteer (E B )

ACKNOWLEDGEMENTS

The authors thank Dr M Lunardelll and Professor F De Martlls for helpful advice and encouragement and Dr. D Dell for helpful crltxlsm and for cor- recting the manuscript

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