Journal of Chromatography B 2010-01-01

Development and validation of a rapid and sensitive assay for simultaneous quantification of midazolam, 1′-hydroxymidazolam, and 4-hydroxymidazolam by liquid chromatography coupled to tandem mass-spectrometry

Miroslav Dostalek, Joyce S. Macwan, Shripad D. Chitnis, Ileana A. Ionita, Fatemeh Akhlaghi, Miroslav Dostalek, Joyce S. Macwan, Shripad D. Chitnis, Ileana A. Ionita, Fatemeh Akhlaghi, Miroslav Dostalek, Joyce S. Macwan, Shripad D. Chitnis, Ileana A. Ionita, Fatemeh Akhlaghi

Index: J. Chromatogr. B. Analyt. Technol. Biomed. Life Sci. 878(19) , 1629-33, (2010)

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Abstract

Midazolam is an ultra short acting benzodiazepine derivative and a specific probe for phenotyping cytochrome P450 (P450) 3A4/5 activity. A rapid, sensitive, and selective LC–MS/MS method was developed for simultaneous quantitation of midazolam and its metabolites (1′-hydroxymidazolam and 4-hydroxymidazolam). Deuterated (D 5) analog of midazolam was utilized as an internal standard. Sample preparation either from human plasma (100 μL) or liver microsomal incubations involved a simple protein precipitation using acetonitrile (900 μL) with an average recovery of >90% for all compounds. The chromatographic separation was achieved using Zorbax-SB Phenyl, Rapid Resolution HT (2.1 mm × 100 mm, 3.5 μm) and a gradient elution with 10 mM ammonium acetate in 10% methanol (A) and acetonitrile (B). The flow rate was 0.25 mL/min and total run time was 5.5 min. Calibration curves were linear over the concentration range of 0.100–250 ng/mL. The lower limit of quantitation (LLOQ) was 0.1 ng/mL for all three analytes. The accuracy and precision, estimated at LLOQ and three concentration levels of quality control samples in six replicates, were within 85–115%. In conclusion, a robust, simple and highly sensitive analytical method was developed and validated for the analysis of midazolam and its metabolites. This method is suitable for characterizing the P450 3A4/5 activity in vitro or in human pharmacokinetic studies allowing administration of smaller doses of midazolam.