Pharmacokinetics And Bioavailability Study Of Compound Glycyrrhizin Injection In Dogs

Pathological changes of the liver are common clinical symptoms in pets,but few drugs are available to relieve the abnormal liver function or the symptoms of inflammation,so it is urgent to develop new liver protection drugs for pets to meet the clinical needs.Compound glycyrrhizin has anti-inflammatory,anti-oxidation,inhibition of apoptosis,inhibition of liver fibrosis,regulation of immunity and other pharmacological actions.It is the most commonly used medicine for liver protection.Tablet,injection and other preparations have been put on the market.It has the characteristics of obvious curative effect,wide adaptability,high safety and low adverse reactions.There are few reports about the related effect of compound glycyrrhizin in pet.In this paper,the UPLC-MS/MS method for the simultaneous determination of glycyrrhizin and glycyrrhetinic acid in dog plasma was established.This method is used to study the pharmacokinetics and bioavailability of Compound Glycyrrhizin Injection in dogs,and to provide basis for the formulation of clinical drug delivery plan for pets.1 Establishment of UPLC-MS/MS method for determination of GL and GA in dog plasmaIn this study,GL and GA in dog plasma were extracted by methanol for two times.After nitrogen blowing and 50%acetonitrile solution redissolving,using the UPLC-MS/MS method to conduct quantitative analysis with external standard method.Results show that the specificity of this method is good and the blank sample has no interference.The LOD and LOQ of GL were 2 μg·L-1 and 5 μg·L-1 respectively,and the LOD and LOQ of GA were 1μg·L-1 and 2 μg·L-1 respectively.In the concentration range of 5-1000 μg·L-1,the peak area has a good linear relationship with the concentration of GL（r2>0.99）;in the concentration range of 2-1000 μg·L-1,the peak area has a good linear relationship with the concentration of GA（r2>0.99）.The recovery rate of GL was 82.45%-114.73%when the concentration of GL was 10,100,500 μg·L-1.The relative standard deviation within and between batches was in the range of 3.05%-13.32%.The recovery rate of GA was 85.18%-114.83%when the concentration of GA was 10,100,500 μg·L-1,and the relative standard deviation within and between batches was in the range of 1.70%-9.11%.It showed that the method was specific,sensitive,accurate and reproducible.It was suitable for the pharmacokinetics study of Compound Glycyrrhizin Injectiong in dogs.2 Pharmacokinetics and bioavailability of Compound Glycyrrhizin Injection in dogsWe used the 2×2 cross test design.Sixteen healthy dogs were separated into two groups randomly.We studied the pharmacokinetics of intravenous injection and subcutaneous injection of compound glycyrrhizin injection,and both groups were injected at a single dose of 1mg·kg-1.B.W.Blood was collected through the cephalic vein of the forelimb at the preset time point,and then isolated plasma.After pretreatment,the plasma samples were measured by UPLC-MS/MS,then calculating the pharmacokinetic parameters.The results show only GL was detected in the collected dog plasma,but no GA was detected.Therefore,only the plasma concentration-time data of GL were analyzed.After single dose intravenous injection（Ⅳ）of Compound Glycyrrhizin Injection,pharmacokinetic parameters of GL are as follows:T1/2λz is（14.02 ± 5.30）h,AUC0→T is（126638.15 ± 24967.83）h·ng·mL-1,MRT0→T is（21.54± 2.57）h,Vd is（163.74 ± 72.67）ml·kg-1,CL is（8.07 ± 1.46）mL·h-1·kg-1.After single subcutaneous injection（SI）of Compound Glycyrrhizin Injection,pharmacokinetic parameters of GL are as follows:T1/2λz is（13.51 ± 4.17）h,Tmax and Cmax are（2.25±0.93）h and（6411.14±1248.11）ng·mL-1 respectively.AUC0→T is（151942.15 ± 34795.59）h·ng·mL1,MRT0→T is（25.81 ± 3.38）h.Vd is（136.75 ± 57.83）ml·kg-1,CL is（6.86 ± 1.64）mL·h-1·kg1.The absolute bioavailability of compound glycyrrhizin injection is 119.98%.The results showed that the compound glycyrrhizin injection was well absorbed subcutaneously in dogs.