Pharmacokinetics And Metabolic Mass Balance Of Aspirin Eugenol Ester In Dogs

The thesis presents a systematic study on the pharmacokinetic and excretory characteristics of aspirin eugenol ester(AEE)in dogs to elucidate the disposition process of AEE in dogs,to explore the metabolic profile regulation of AEE in normal canine organism using metabolomic approach,to provide a basis for a comprehensive evaluation of the pharmacological properties of AEE and to provide a reference for rational clinical drug use.1.A method for the quantification of AEE and its active metabolites ASA,SA and EUG in canine plasma by HPLC-MS/MS was established.The linearity range,specificity,accuracy,precision,dilution reliability,extraction recovery,matrix effect and stability of the method met the requirements of pharmacokinetic studies.The absorption of AEE was measured in vivo after gavage administration of 8mg/kg,20 mg/kg and 48 mg/kg of AEE suspension,oral administration of 20 mg/kg of AEE(tablets)and intravenous administration of 8 mg/kg of AEE in dogs,respectively,and pharmacokinetic parameters were calculated.The results showed that both AEE and the metabolite ASA were undetectable in plasma;the metabolite EUG had a low concentration in plasma and did not reach the limit of quantification at all three doses;the metabolite SA had a large blood concentration with a peak time of about 2 h.The pharmacokinetic parameter AUC of SA was linearly correlated with the administered dose;after gavage administration of three different doses of AEE suspension in dogs The absolute bioavailability of SA was 20.48%,9.43%and 7.98%after gavage administration of three different doses of AEE suspension in dogs,respectively;the absolute bioavailability of AEE tablets after oral administration reached 69.9%.2.An HPLC-MS/MS method was developed and validated for the determination of 13 major metabolites of AEE in canine urine and faecal matrices.The results showed that the method was specific and sensitive;the linear concentration range was 50-10000 ng/m L(R~2>0.99);all 13 metabolites of AEE in urine and faecal matrices were extracted with recoveries greater than 67.7%and calibrated for bias due to matrix effect sample detection using matrix-matched standard curves and isotopic internal standard methods;the intra-and inter-batch precision was less than 15.0%and the accuracy ranged from-9.6 to 13.0%;the 13 metabolites of AEE were stable under different treatment conditions.3.AEE was administered to dogs at 20 mg/kg by gavage,and urine and faeces were collected from0 to 120 h.The concentrations of the 13 metabolites of AEE in urine and faeces were determined,and the excretion of each metabolite was analysed as a proportion of the administered dose.The results showed that the recovery of metabolites of AEE in urine and faeces with ASA as the parent nucleus was71.48±8.32%,of which urinary excretion was 65.08±7.56%;the excretion of metabolite SA was the largest,accounting for 53.53%,the excretion of phase II metabolites of SA,SUA,SAG and SAAG,accounted for 45.87%,and the excretion of phase I metabolite GA accounted for only 1.24%;the recovery of metabolites with EUG as the parent nucleus was 76.49±11.39%,of which urinary excretion was 70.51±10.59%.The metabolite EUG and its phase II metabolites E-S and E-G accounted for the largest amount of excretion at 78.90%,followed by the phase I metabolite Acid,which accounted for17.90%of the excretion,while the total excretion of the remaining phase I metabolites was only 2.99%.4.The results of plasma and urine metabolomics studies in dogs showed that the metabolic profiles before and after AEE administration were clearly distinguished,revealing that AEE is mainly involved in the metabolism of glycerophospholipids,arachidonic acid metabolism,folic acid biosynthesis,tryptophan metabolism,the interconversion of pentose and glucuronide cysteine and methionine metabolism and glutathione metabolism,etc.The above processes of AEE may have an impact on the body’s hyperlipidemia and AEE may play a regulatory role in the development of diseases such as hyperlipidemia and atherosclerosis.In summary,AEE exists in vivo mainly in the form of its active metabolite SA;the oral absolute bioavailability of AEE suspension is low and the oral bioavailability of tablets is high;AEE is biotransformed and extensively metabolized in dogs,and its metabolites are mainly excreted through urine;AEE can interfere with the body’s glycerophospholipid metabolism,arachidonic acid metabolism and glutathione metabolism and other 10 metabolic pathways.