During the preclinical study of the original functional peptide, SR-0379, a sensitive liquid chromatographytandem
mass spectrometry method was newly developed to study the pharmacokinetics of SR-0379 in rat plasma and subcutaneous
tissue samples. Although SR-0379 was unstable in the rat plasma and subcutaneous tissue samples, pretreatment
with EDTA and phosphoric acid (4 %) inhibited its degradation. The lower limits of quantification (LLOQ) for SR-
0379 were fully validated as 5 ng/ml in plasma and 5 ng/g in tissue with acceptable linearity, intra- and inter-assay precisions,
and accuracy. Measurement of SR-0379 concentration in plasma after intravenous injection via LC-MS/MS yields
plasma concentration-time curves (AUC0-∞) with areas of 667 ng•min/ml and an elimination half-life (t1/2) of 4.8 min. The
concentration of SR-0379 in the subcutaneous tissue samples was 13.1 µg/g tissue at 30 minutes after a single dermal application
(1 mg/ml, 50 µl) to a full-thickness excisional wound. Here, a highly sensitive and specific LC-MS/MS assay
with a lower limit of quantification of 5 ng/ml was developed and validated to quantify SR-0379 in rat plasma. This
method is useful for pharmacokinetic studies of the peptide drugs in rats.
Keywords: LC-MS/MS, pharmacokinetics, plasma, quantitation, subcutaneous tissue.
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