| Pharmacokineties(PK)is a discipline that quantitatively analyzes the absorption,distribution,metabolism,and excretion of drugs in the body,and uses the principle of dynamics to study changes in plasma drug concentration over time.An ideal lead compound not only needs to have better efficacy and less toxic side effects,but also must have good pharmacokinetic properties.Pharmacokinetics is as important as pharmacodynamics and toxicology in the development of new drugs,and it has become an important part of drug design and development.Our previous study found that oleanolic acid,a natural product extracted from Achyranthes bidentate,possessed an inhibitory effect on bone resorption.By modifying the structure of oleanolic acid,we obtained a series of derivatives and discovered some compounds with good anti-osteoporosis activity.Among them,HA-19 showed the best dual roles in promoting bone formation and inhibiting bone resorption.Interestingly,this compound also showed significant inhibitory effect on disuse muscular atrophy both in vitro and in vivo.In order to investigate the druggability of HA-19,the pharmacokinetics and tissue distribution characteristics of HA-19 were studied,which laid the foundation for better study the target organs and possible mechanism of such compounds.1.Pharmacokinetics of HA-19 in SD ratsA rapid and sensitive liquid chromatography-mass spectrometry(LC-MS)method was established to analyze the concentration of HA-19 in the plasma of SD rats,then the pharmacokinetic properties of HA-19 was investigated.HA-19,and an internal standard(8aIS)in rat plasma samples were extracted by methanol and analyzed by LC-MS after centrifugation.Column:Xbridge C18(2.1 mm×150 mm,3.5 ?m);mobile phase:0.1%formic acid water-0.1%formic acid acetonitrile,starting ratio 80:20,gradient elution,flow rate:0.3 ml/min;temperature control:30?Measurement of HA-19 was performed by positive ion electro spray ionization in multiple reaction monitoring mode,monitoring the transitions m/z 686.50?628.20 and m/z 582.45?409.40 for HA-19 and 8aIS,respectively.The results showed that the method was highly specific,efficient and sensitive,and could be used for the pharmacokinetic analysis of HA-19 in SD rats.Rats were divided into intravenous and oral administration groups with 6 SD rats per group.The pharmacokinetic parameters were calculated using DAS software according to the drug concentration measured at different times.The two-compartment model was used to analyze the plasma drug concentration-time curve of the oral administration group.The Cmax was 23.566 ?g/1,the Tmax was 4 h,and the AUC(0-t)was 121.39 ?g/l*h.The t1/2z is 2.317 h.The three-compartment model was used to analyze the plasma drug concentration-time curve of the intravenous administration group.The AUC(0-t)was 191.599 ?g/l*h,the t1/2a was 0.169 h,the t1/2?is 1.319 h and the t1/2? is 26.694 h.The absolute bioavailability of HA-19 in SD rats was 6.34%.2.Tissue distribution study on HA-19 in SD ratsA LC-MS method was established to analyze the concentration of HA-19 in nine organs(liver,heart,spleen,stomach,kidney,muscle,fat,pancreas,duodenum)of SD rats after oral administration one day and 7 weeks to understand the tissue distribution characteristics of HA-19.HA-19,and an internal standard(8aIS)in rat plasma samples were extracted by ethyl acetate and analyzed by LC-MS after centrifugation.Column:Xbridge C18(2.1 mm ×50 mm,2.5 ?m);mobile phase:0.1%formic acid water-0.1%formic acid acetonitrile,ratio 95:5,isocratic elution,flow rate:0.2 ml/min;temperature control:35?.Measurement of HA-19 was performed by positive ion electro spray ionization in multiple reaction monitoring mode,monitoring the transitions m/z 686.60?628.08 and m/z 582.40?409.75 for HA-19 and 8aIS,respectively.The results showed that the method was highly specific,efficient and sensitive,and could be used for the tissue distribution study of HA-19 in SD rats.The concentration of HA-19 in the stomach and duodenum of SD rats after administration was higher than those in other tissues.In most tissues,the concentration of HA-19 reached to the peak concentrations at the time of 0.5 h or 1 h which showed that HA-19 could be rapidly distributed.The higher concentration of HA-19 in the muscle suggested that muscle tissue might be one of the target organs of HA-19,which provided preliminary evidence for its inhibitory effect on muscle atrophy in vivo,and also suggested that the anti-osteoporosis activity of HA-19 might be related to the interaction between bone and muscle.Comparing to the results of one-day and seven-week,we found that there was an accumulation of HA-19 in the liver,fat and pancreas. |
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