Development of a UHPLC-MS/MS Method for the Determination of Omadacycline in Human Plasma

Omadacycline is a novel aminomethylcycline antibiotic that retains its antibacterial activity against strain-specific efflux pumps and ribosomal protective protein mechanisms of tetracycline resistance. To determine the concentration of omadacycline in human plasma, an ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed to provide a basis for therapeutic monitoring of omadacycline in clinical settings. The experimental approach involves using an ACQUITY UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm), with a mobile phase of 0.1% aqueous formic acid:acetonitrile (90:10, vol/vol), a flow rate of 0.3 mL·min -1 , a column temperature of 40°C, and an injection volume of 0.1 μL. Protein precipitation was employed as pretreatment, using acetonitrile as the precipitant. Minocycline was used as an internal standard. Omadacycline and internal standard were monitored in positive ion mode with the following mass transition pairs: mass/charge (m/z) = 557.1→ 470.1 for omadacycline, and m/z = 458.3→ 440.9 for IS, respectively. The established method showed a good linearity in the range of 0.01-10 mcg/mL of omadacycline (Y = 0.4603X + 0.0452, r 2 = 0.999), with the lower limit of quantification of 0.01 mcg/mL. Method validation included accuracy, precision, matrix effect, recovery, carryover, dilution integrity, and stability, all of which met the requirements of the US Food and Drug Administration for the validation of bioanalytical methods. This method has been successfully applied to therapeutic drug monitoring in patients.