Affiliation: | a Laboratory of Pharmacokinetics (FATC 7355), School of Pharmacy, Catholic University of Louvain, B-1200 Brussels, Belgium b Department of Gastroenterology, University Hospital St. Luc, Catholic University of Louvain, B-1200 Brussels, Belgium c Beun-De Ronde Serlabo (BRS), Rue J. Broeren 36, B-1070 Brussels, Belgium d Laboratory of Pharmacokinetics (FATC 7355), School of Pharmacy, Catholic University of Louvain, Avenue E. Mounier 73, B-1200 Brussels, Belgium |
Abstract: | A sensitive high-performance liquid chromatographic method is described for the quantification of midazolam and 1′-hydroxymidazolam in human plasma. Sample (1 ml plasma) preparation involved a simple solvent extraction step with a recovery of approximately 90% for both compounds. An aliquot of the dissolved residue was injected onto a 3 μm capillary C18 column (150 mm×0.8 mm I.D.). A gradient elution was used. The initial mobile phase composition (phosphate buffer–acetonitrile, 65:35) was maintained during 16 min and was then changed linearly during a 1-min period to phosphate buffer–acetonitrile, 40:60. The flow-rate of the mobile phase was 16 μl/min and the eluate was monitored by UV detection. The limits of quantification for midazolam and 1′-hydroxymidazolam were 1 ng/ml and 0.5 ng/ml, respectively. The applicability of the method was demonstrated by studying the pharmacokinetics of midazolam, and its major metabolite 1′-hydroxymidazolam, in human volunteers following i.v. bolus administration of a subtherapeutic midazolam dose (40 μg/kg). |