Comparative Study On Pharmacokinetics Of Glibenclamide Between Normal Rats And Two Models Of Diabetic Rats

ObjectivesThe aim of this study was to compare the pharmacokinetics differences of glibenclamide by intragastrical/intravenous administration between normal rats and two models of diabetic rats, and the mechanism of difference was preliminarily clarified.Methods1. Wistar rats were divided into3groups, A:normal rats （normal group）; B:streptozotocin （STZ） induced diabetic rats （STZ group）; C:high-energy diet plus STZ induced diabetic rats （high-energy group）. Normal group and STZ group were fed with normal diet for6weeks, the rats in high-energy group were fed with high-energy diet for6weeks. At the end of the6th week, after all the rats were fasted for16h, STZ group were injected intraperitoneally with60mg/kg STZ, high-energy group were injected intraperitoneally25mg/kg STZ, normal group were given corresponding volume of sodium citrate buffer solution intraperitoneally.3days later, the fasting plasma of all the rats was collected by amputation of tail. Whose blood sugar value exceeded12.9mmol/L determined by the glucose oxidase method was successful diabetic mold.2.3groups were given10mg/kg glibenclamide intragastrically. Plasma was collected from femoral artery of rats at different time points, and plasma concentration was detected by HPLC. Pharmacokinetic parameters were calculated using DAS2.0software and were compared.3.3groups of rats were injected intravenously of5mg/kg glibenclamide. Plasma was collected from femoral artery of rats at different time points, and plasma concentration was detected by HPLC. Pharmacokinetic parameters were calculated using DAS2.0software and they were compared to understand whether or not there was any difference between normal rats and two modles of diabetic rats.4. The difference of intesital absorption of glibenclamide was carried out by the method of in situ single-pass intestinal perfusion in3groups of rats.5. Diclofenac sodium （a substrate of CYP2C9） was injected10mg/kg via caudal vein to evaluate the change of hepatic drug-metabolizing enzyme activity in rats. Plasma were collected from femoral artery of rats at different time points, and plasma concentration was detected by HPLC. Pharmacokinetic parameters were calculated using DAS2.0software and were compared to examine the changes of hepatic drug metabolizing enzyme CYP2C9activity in the3groups of rats.6. The expression of liver CYP2C9was semi-quantitatively analyzed by Western blot in3groups of rats.Results1. Given glibenclamide10mg/kg intragastrically, the pharmacokinetic values in STZ group were significant different from normal group and high-energy group. The AUC（0₇20min）（321.24mg-min/L） in STZ group was greater than that （57.752mg-min/L） in normal group and （90.257mg-min/L） in high-energy group significantly （P<0.05）; Cmax （0.910μg/mL） in STZ group was greater than that （0.259μg/mL） in normal group and （0.230ug/mL） in high-energy group significantly （P<0.05）; Tmax （255.427min） in STZ group was longer then that （84.784min） in normal group and （0.230μg/mL） in high-energy group significantly （P<0.05）; CL （0.019L/min/kg） in STZ group was significantly slower than that （0.092L/min/kg） in normal group and （0.087L/min/kg） in high-energy group （P<0.05）. Compared with normal group, there was no significant difference in high-energy group （P>0.05）.2. Given glibenclamide5mg/kg intravenously, the pharmacokinetic parameters of glibenclamide were also changed significantly in normal group, STZ group and high-energy group. The AUC（0-480min）（1528.280mg-min/L） in STZ group were significantly higher then that （509.523mg-min/L） in normal group and （622.733mg-min/L） in high-energy group （P<0.05）; T1/2（560.902min） in STZ group were significantly longer then that （225.466min） in normal group and （300.559min） in high-energy group （P<0.05）; CL （2.667×103L/min/kg） in STZ group was significantly slower than that （7.612×103L/min/kg） in normal group and （5.899×103L/min/kg） in high-energy group （P<0.05）. Compared with normal group, there was no significant difference in high-energy group （P>0.05）.3. No significant difference was found in3groups of rats about intesital absorption of glibenclamide （P>0.05）.4. Given diclofenac sodium10mg/kg intravenously, the pharmacokinetic parameters of diclofenac sodium were also changed significantly in normal group, STZ group and high-energy group as followed:The AUC（0-480min）（1468.445mg·min/L） in STZ group were significantly higher then that （684.604mg·min/L） in normal group and （662.425mg·min/L） in high-energy group （P<0.05）; T1/2（288.930min） in STZ group were significantly longer then that （170.076min） in normal group and （162.043min） in high-energy group （P<0.05）; CL （2.667×103L/min/kg） in STZ group was significantly slower than that （7.612×103L/min/kg） in normal group and （5.899×103L/min/kg） in high-energy group （P<0.05）. Compared with normal group, there was no significant difference in high-energy group （P>0.05）.5. Protein expression of hepatic CYP2C9measured by Western blot analysis was as followed: compared with normal rats, the CYP2C9protein expression decreased in STZ induced diabetic rats （P<0.05）. There was no difference between high-energy diet plus STZ induced diabetic rats and normal rats （P>0.05）.ConclusionsPharmacokinetic parameters of glibenclamide in STZ induced diabetic rats were significantly different from normal rats and high-energy diet plus STZ induced diabetic rats. Compared with normal group and high-energy group, elimination was decreased in STZ group. Compared with normal group, there was no significant difference in high-energy group.The one of main mechanisms of the glibenclamide pharmacokinetics differences in3groups of rats was mainly due to the lower expression of hepatic CYP2C9in STZ induced diabetic rats.