A simple and fast determination of plasma panipenem (PAPM) in extremely low birth weight infants was established using reversed phase high-performance liquid chromatography. Solutions of 35% methanol (pH 5.8), including 5 mM NaH2PO4 and 5 mM sodium dodecylsulfate, were used for the mobile phase. The flow rate was 0.8 mL/min. UV detection was carried out at 300 nm. The pretreatment method was as follows: 200 mM 3-[morpholino] propansulfonic acid solution was added to the plasma as a stabilizer. It was then deproteinized with methanol. The calibration curve was linear in a range from 6.25μg/mL to 100μg/mL. The recovery rate from known concentration samples of PAPM was 98.4%. The within-run and day-to-day variations were below 2.5% and 2.7%, respectively. The PAPM concentrations in the plasma were determined in five infants. In immature patients, an extension of the half-life was also observed.
