The application of a new microfluidic device for the simultaneous identification and quantitation of midazolam metabolites obtained from a single micro-litre of chimeric mice blood.
BACKGROUND
Improvements in the design of low-flow highly sensitive chromatographic ion source interfaces allow the detection and characterisation of drugs and metabolites from smaller sample volumes. This in turn improves the ethical treatment of animals by reducing both the number of animals needed and the blood sampling volumes required.


METHODS
A new microfluidic device combining an ultra-high pressure liquid chromatography (UHPLC) analytical column with a nano-flow electrospray source is described. All microfluidic, gas and electrical connections are automatically engaged when the ceramic microfluidic device is inserted into the source enclosure. The system was used in conjunction with a hybrid quadrupole-time-of-flight mass spectrometer.


RESULTS
The improved sensitivity of the system is highlighted in its application in the quantification and qualification of midazolam and its metabolites detected in whole blood from chimeric and wild-type mice. Metabolite identification and full pharmacokinetic profiles were obtained from a single micro-litre of whole blood at each sampling time and significant pharmacokinetic differences were observed between the two types of mice.


CONCLUSIONS
Improvements in the enhanced ionisation efficiency from the microfluidic device in conjunction with nanoUHPLC/MS was sufficiently sensitive for the identification and quantification of midazolam metabolites from a single micro-litre of whole blood. Detection of metabolites not previously recorded from the chimeric mouse in vivo model was made.
Oncology iMed DMPK, AstraZeneca UK Ltd., Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK.
Richard
R
Gallagher
Leonard
L
Dillon
Aidan
A
Grimsley
Jim
J
Murphy
Kristin
K
Samuelsson
David
D
Douce
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D008874:Midazolam / Q000097:blood* / Q000737:chemistry* / Q000493:pharmacokinetics; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization
D008874:Midazolam