Objective: To establish an LC-MS/MS method for the quantitive determination of vonoprazan in Beagle dog plasma and study its toxicokinetics. Methods: 40 Beagle dogs with half males and half females were randomly divided into vehicle control group(0.9% sodium chloride injection), low-dose group(1 mg·kg-1·d-1), medium-dose group(3 mg·kg-1·d-1)and high-dose group(10 mg·kg-1·d-1). They were given medicine once a day for consecutive 4 weeks by intravenous administration. The blood samples were drawn from the subcutaneous vein(the forelimb legs) on the first dose 0 h before medication and the last dose 1/12, 0.5, 1, 2, 4, 7, 10 and 24 h after medication. The plasma samples were extracted with protein precipitation and then analyzed by LC-MS/MS method. The separation was carried out on an ODS column(2.1 mm×100 mm, 5 μm), with mobile phase acetonitrile/formic acid(adjusted to pH 3.24 with ammonium hydroxide)(40:60, v/v)at a flow rate of 0.2 mL·min-1. Lansoprazole was used as the internal standard. An electrospray ionization(ESI)source was applied and the mass spectrometer was operated in positive MRM mode. Quantitative analysis of vonoprazan 10 mg·kg-1 and lansoprazole were at m/z:346.30 → 315.20 and m/z:370.30 → 252.30, respectively. The toxicokinetics parameters were analyzed by DAS2.1. Results: Quantification of vonoprazan showed a good linear relationship over the range of 5-5 000 ng·mL-1(r=0.999 6). The minimum quantitative limit was 5 ng·mL-1. The intra-day and inter-day precisions(RSDs)were less than 7.7% and the extraction recoveries exceeded 91.6%. Matrix effects were 106%-114%. Extraction recovery and matrix effect of the standard were(97.3±0.76)% and(100.6±0.90)%. The stability of RSD was<4.7%. Main toxicokinetics parameters of Vonoprazan in Beagle dogs at low-dose, medium-dose and high-dose group with first dosage were as follows:Cmax:(0.54±0.03), (1.30±0.20), (3.51±0.52)μg·L-1;AUC(0-24):(1.35±0.24), (5.13±0.94), (23.74±3.12)mg·h·L-1;t1/2:(1.77±0.30), (2.37±0.29), (3.71±0.39)h. Main toxicokinetics parameters of vonoprazan in Beagle dogs at low-dose, mediumdose and high-dose group with last dosage were as follows:Cmax:(0.53±0.09), (1.44±0.26), (5.05±0.64)μg·L-1; AUC(0-24):(1.29±0.25), (4.92±0.97), (25.25±2.96)mg·h·L-1;t1/2:(1.56±0.26), (2.11±0.34), (3.51±0.33)h. At the range of 1-10 mg, the confidence intervals and the critical region of AUC(0-24), AUC(0-∞)and Cmax were overlapped. Conclusion: The results reveal that this method is sensitive, specific, stable and accurate. It is suitable for the analysis of vonoprazan in plasma samples. The drug has no gender difference and no significant accumulation effect in Beagle dogs after repeated dosing for 28 days, and it is still uncertain if the drug has linear dose-dependent kinetics.
