High-performance liquid chromatographic assay for metamizol metabolites in rat plasma: application to pharmacokinetic studies.
In order to evaluate the pharmacokinetics of metamizol in the presence of morphine in arthritic rats, after subcutaneous administration of the drugs, an easy, rapid, sensitive and selective analytical method was proposed and validated. The four main metamizol metabolites (4-methylaminoantipyrine, 4-aminoantipyrine, 4-acetylaminoantipyrine and 4-formylaminoantipyrine) were extracted from plasma samples (50-100μl) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography with diode-array detection. Standard calibration graphs for all metabolites were linear within a range of 1-100μg/ml (r(2)≥0.99). The intra-day coefficients of variation (CV) were in the range of 1.3-8.4% and the inter-day CV ranged from 1.5 to 8.4%. The intra-day assay accuracy was in the range of 0.6-9.6% and the inter-day assay accuracy ranged from 0.9 to 7.5% of relative error. The lower limit of quantification was 1μg/ml for all metabolites using a plasma sample of 100μl. Plasma samples were stable at least for 4 weeks at -20°C. This method was found to be suitable for studying metamizol metabolites pharmacokinetics in arthritic rats, after simultaneous administration of metamizol and morphine, in single dose.
Departamento Sistemas Biológicos, UAM-Xochimilco, Calzada del Hueso 1100, Col. Villa Quietud, 04960 México D.F., Mexico. adoming@correo.xoc.uam.mx
Adriana Miriam
AM
Domínguez-Ramírez
Patricia Carrillo
PC
Calzadilla
Alma Rosa
AR
Cortés-Arroyo
Marcela
M
Hurtado Y de la Peña
José Raúl Medina
JR
López
Martín
M
Gómez-Hernández
Francisco Javier
FJ
López-Muñoz
D000632:Aminopyrine / Q000031:analogs & derivatives / Q000097:blood / Q000737:chemistry; D000675:Ampyrone / Q000031:analogs & derivatives / Q000097:blood / Q000737:chemistry; D000818:Animals; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000379:methods; D004177:Dipyrone / Q000031:analogs & derivatives / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics*; D004347:Drug Interactions; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D052616:Solid Phase Extraction / Q000379:methods
D000632:Aminopyrine; D000675:Ampyrone; C011256:4-formylaminoantipyrine; D004177:Dipyrone; D009020:Morphine; C010403:N-acetylaminoantipyrine; C008667:noramidopyrine