Measurement by HPLC of Midazolam and its Major Metabolite 1-Hydroxymidazolam in Plasma of Very Premature Neonates

✍ Scribed by Toong Chow Lee; Bruce Charles

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 360 KB
• Volume: 10
• Category: Article
• ISSN: 0269-3879
• DOI: 10.1002/(sici)1099-0801(199603)10:2<65::aid-bmc555>3.0.co;2-q

✦ Synopsis

A simple, selective high-performance liquid chromatographic method with ultraviolet detection at 220 nm is described for quantitation of midazolam and its primary metabolite 1-hydroxymidazolam in 100 pL plasma samples from premature infants. A mobile phase of acetonitrile: tetrahydr0furan:phosphate buffer (0.01 M, pH6.7) (35:5:60 v/v) was pumped at 1 mL/min through a C, Symmetrym (150x39 mm) column. Plasma (100 pL) was extracted with 10% v/v isopropyl alcohol in dichloromethane containing 25 ng/mL climazolam (internal standard, IS) followed by back extraction into phosphoric acid (0.02 M). 1-Hydroxymidazolam, midazolam, and climazolam (IS) were eluted at 4.9, 7.4, and 8Amin, respectively. Recoveries were >70%. Calibration curves in blank plasma were linear (r>0.999) from 12.5 to 800 ng/mL. Within-day and between-day imprecision (CV%) was 1.8-6.5%, and 4.1-8.8%, respectively. Inaccuracy was 12.3%. Application of the method was demonstrated by a pharmacokinetic analysis of midazolam and 1-bydroxymidazolam in plasma drawn from 15 premature neonates after a single intravenous dose of midazolam (0.1 mg/kg).