title: Simultaneous determination of flumazenil, midazolam and metabolites in human biological fluids by liquid chromatography.
abstract: A simple procedure for the simultaneous determination of flumazenil, midazolam, 1-hydroxymethylmidazolam and 4-hydroxymidazolam in plasma or urine in surgical patients is described. The assay involves a preliminary extraction of the drugs, metabolites and internal standard (flurazepam) from biological fluid into an organic solvent mixture (dichloromethane-diethyl ether, 40:60 v/v). The extract was evaporated to dryness at 40 degrees C under a gentle stream of nitrogen. The residue was re-dissolved in distilled methanol (80 microliters) and a 30-microliters aliquot was injected via an automatic sampler into the liquid chromatograph and eluted with the mobile phase (32% acetonitrile in 0.004 M sodium hydrogenphosphate buffer containing 1 ml of triethylamine and adjusted to pH 7.2) at a flow-rate of 1.5 ml/min on a 30-microns C8 precolumn linked to a 4-microns Nova-pak C18 cartridge column (100 mm x 8 mm I.D.) at ambient temperature (25 degrees C). The eluate was detected at 220 nm.
authors.affiliation: Department of Pharmacology, Chinese University of Hong Kong, Shatin.
authors.forename: K
authors.initials: K
authors.lastname: Chan
authors.forename: R D
authors.initials: RD
authors.lastname: Jones
mesh_terms: D002648:Child; D002851:Chromatography, High Pressure Liquid; D005442:Flumazenil / Q000032:analysis* / Q000493:pharmacokinetics; D006801:Humans; D007202:Indicators and Reagents; D008874:Midazolam / Q000032:analysis* / Q000493:pharmacokinetics; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007202:Indicators and Reagents; D005442:Flumazenil; D008874:Midazolam