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The purpose of this work was to develop and validate an HPLC-MS/MS method suitable for quantifying two important cardiovascular drugs, milrinone and dobutamine, in neonatal and paediatric patients’ blood plasma samples. Sufficiently low LLOQ levels were required to obtain adequate pharmacokinetic data for the evaluation of optimal dosing. Since the specifics of the patient group set some restrictions on the available sample volume, the method was designed to use only 20 µL of plasma for the analysis. Analytes were separated chromatographically in a biphenyl column using a conventional water-methanol-formic acid eluent with the addition of ammonium fluoride. The latter provided a significant signal enhancement in positive ion mode detection for both analytes allowing the LLOQ to reach below 1 ng/mL. Matrix matched calibration was linear in the range of 1–300 ng/mL, between-run accuracy remained within 107–115%, and precision within 4.8–7.4% for both analytes over the calibration range (including LLOQ level). Dobutamine degradation in plasma samples was prevented by the usage of ascorbic acid. The method was applied to plasma samples of neonates from two pharmacokinetic/pharmacodynamics studies (n = 38).

In intensive care units, the precise administration of sedatives and analgesics is crucial in order to avoid under- or over sedation and for appropriate pain control. Both can be harmful to the patient, causing side effects or pain and suffering. This is especially important in the case of pediatric patients, and dose-response relationships require studies using pharmacokinetic-pharmacodynamic modeling. The aim of this work was to develop and validate a rapid ultra-high performance liquid chromatographic-tandem mass spectrometric method for the analysis of three common sedative and analgesic agents: morphine, clonidine and midazolam, and their metabolites (morphine-3-glucuronide, morphine-6-glucuronide and 1'-hydroxymidazolam) in blood plasma at trace level concentrations. Low concentrations and low sampling volumes may be expected in pediatric patients; we report the lowest limit of quantification for all analytes as 0.05ng/mL using only 100μL of blood plasma. The analytes were separated chromatographically using the C18 column with the weak ion-pairing additive 1,1,1,3,3,3-hexafluoro-2-propanol and methanol. The method was fully validated and a matrix matched calibration range of 0.05-250ng/mL was attained for all analytes In addition, between-day accuracy for all analytes remained within 93-108%, and precision remained within 1.5-9.6% for all analytes at all concentration levels over the calibration range.