A simplified and sensitive LC-APCI-MS/MS method for the quantification of propofol: Application to a bioequivalence study in healthy Chinese subjects

Propofol has become the preferred anesthetic in recent years due to its desirable pharmacologic properties. However, propofol possesses a very narrow therapeutic window between the favorable clinical effect and potentially lethal toxicity, therefore, a rapid, simplified, and sensitive liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) method is presented in this study for the quantification of propofol in human plasma using the isotope-labeled internal standard (IS) of propofol-d17, and then applied in a bioequivalence study.Sample preparation was accomplished through simple one-step precipitation of plasma protein with acetonitrile. Chromatographic separation was acquired on an ACE Excel 3 Super C18 column (2.1 × 50 mm, 3 µm) using gradient elution at a flow rate of 0.5 mL/min. The MS detection was achieved in the negative ion APCI by multiple reaction monitoring (MRM) mode using the transitions of m/z 177.2 → 161.0 for propofol and m/z 194.2 → 174.2 for IS, respectively. 30 healthy Chinese subjects were enrolled in the open-label, randomized, two-period, two-sequence, cross-over bioequivalence study after single-dose intravenous administration of propofol medium-chain triglyceride and long-chain triglyceride (MCT/LCT).The current method was precise and accurate at a linearity range of 4.00 - 1,000 ng/mL without severe interference from the plasma matrix. The inter- and intra-batch precision (2.3 to 15.8%) and accuracy (-4.4 to 3.0%), IS-normalized matrix effect (coefficient of variation ≤ 4.6%), extraction recovery (107.1 - 117.1%), stability (coefficient of variation ≤ 8.0%), and dilution integrity were all within the acceptable range. The 90% confidence intervals (CIs) of the ratios of the geometric means (test/reference) were 86.44 - 104.88% for Cmax, 96.30 - 104.52% for AUC0-t, and 96.56 - 105.05% for AUC0-∞, which were all within the predefined bioequivalence range of 80 - 125%. Besides, both propofol MCT/LCT preparations were well tolerated in healthy Chinese subjects, and there were no serious adverse events during the study.The method is more simplified and sensitive than the previously reported modes of propofol detection. The two propofol MCT/LCT preparations were considered to be bioequivalent.