title: High-performance liquid chromatographic determination of the polar metabolites of nifedipine in plasma, blood and urine.
abstract: A relatively simple reversed-phase high-performance liquid chromatographic method for the determination of the polar metabolites of nifedipine in biological fluids is described. After conversion of 2-hydroxymethyl-6-methyl-4-(2-nitrophenyl)pyridine-3,5-dicarboxylic acid 5-methyl ester (IV) into 5,7-dihydro-2-methyl-4-(2-nitrophenyl)-5-oxofuro[3,4-b] pyridine-3-carboxylic acid methyl ester (V) by heating under acidic conditions, V was extracted with n-pentane-dichloromethane (7:3) and analysed on a C18 column with ultraviolet detection. Subsequently, 2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylic acid monomethyl ester (III) was extracted with chloroform and analysed on the same system. Limits of determination in blood were 0.1 microgram/ml for III and 0.05 microgram/ml for IV and V; these limits were two to ten times higher for urine. This inter-assay variability was always less than 7.5%.
authors.affiliation: Division of Pharmacology, University of Leiden, The Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: Roosemalen
authors.forename: P A
authors.initials: PA
authors.lastname: Soons
authors.forename: T
authors.initials: T
authors.lastname: Funaki
authors.forename: D D
authors.initials: DD
authors.lastname: Breimer
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D007275:Injections, Intravenous; D008297:Male; D009543:Nifedipine / Q000008:administration & dosage / Q000032:analysis* / Q000097:blood / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009543:Nifedipine