RESUMO
Objective To develop a solid-phase extraction and HPLC method for the determination of midazolam and its hydroxy metabolites in child plasma. Methods Blood plasma samples were collected twenty four hours after treated with midazolam by continuous infusion of 2μg·kg-1·min-1 in our intensive care unit, the concentration of midazolam and its metabolites in plasma was detected by solid-phase extraction and RP-HPLC. The separation was performed on ZORBAX Eclipse XDB～C18 column(4.6 ×250mm,5μ m) with 7.56mmol/L ammonium sulfate - acetonitrile as mobile phase. The flow rate was 1.0ml/min,the column temperature was 25℃ and the wavelength of UV detector was 254nm. Results The retention time of 4-hydroxymidazolam, 1'-hydroxymidazolam and midazolam was detected as 8.14,9.09 and 11.18 min. The average recoveries for midazolam and its metabolites was 98.88% ～100.01% ,and RSD ＜ 4%. 29 patients took part in the study, the average plasma concentration of midazolam, 1'-hydroxymidazolam and 4-hydroxymidazolam was 0.68,0.28 and 0.08mg/L. Conclusion It is suitable for convention monitoring of the midazolam and its hydroxy metabolites concentration in the plasma