title: Determination of midazolam and 1-hydroxymidazolam from plasma by gas chromatography coupled to methane negative chemical ionization mass spectrometry after sublingual administration of midazolam.
abstract: A sensitive and selective gas chromatographic mass spectrometric method for the determination of midazolam and its biologically active metabolite, 1-hydroxymidazolam, in rabbit plasma has been developed and validated. Sample preparation includes mixed-mode solid-phase extraction and derivatization with silylating reagents. Midazolam-d4 was used as an internal standard for the determination of parent drug and its active metabolite. The instrumentation consisted of a capillary column gas chromatography and a single quadrupole mass spectrometer with a negative chemical ionization. The method was found to be valid in terms of selectivity, linearity, precision, accuracy, and recovery over the concentration range of 2-200 ng/ml and 1-100 ng/ml for midazolam and 1-hydroxymidazolam, respectively. For both analytes, the lower limit of quantification was 2 ng/ml. Midazolam was stable in stock solutions stored three months at -20°C and in human plasma stored for three months at -80°C. In addition, no degradation of midazolam was found after three freeze-thaw cycles, in short-term stability at room temperature for 24h, or in post-preparative stability in the autosampler. The validity of the method was further tested by performing a pharmacokinetic study of sublingual administration of midazolam in rabbits. The method will be used in studies related to a formulation development of novel midazolam formulations for use in paediatric anaesthesia.
authors.affiliation: School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland.
authors.forename: Ruut
authors.initials: R
authors.lastname: Kaartama
authors.forename: Pekka
authors.initials: P
authors.lastname: Jarho
authors.forename: Jouko
authors.initials: J
authors.lastname: Savolainen
authors.forename: Hannu
authors.initials: H
authors.lastname: Kokki
authors.forename: Marko
authors.initials: M
authors.lastname: Lehtonen
mesh_terms: D000286:Administration, Sublingual; D000818:Animals; D019540:Area Under Curve; D004355:Drug Stability; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D008697:Methane / Q000737:chemistry; D008874:Midazolam / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction
chemical_list: C040081:1-hydroxymethylmidazolam; D008697:Methane; D008874:Midazolam