Based On ROCTs And RMATE1 Exploring The Effects Of Enalapril And Telmisartan On Pharmacokinetics Of Metformin In Rats

ObjectivesThe study is aimed to investigate the effects of enalapril and telmisartan on the pharmacokinetics of metformin in rats,and further to explore the underlying mechanism.Methods1 Effects of enalapril on pharmacokinetics of metformin in rats1.1 The groups setting of animals and drug administration:a total of 12 rats were randomly divided into control group（metformin,100 mg/kg;p.o.）and co-administration group（metformin,100 mg/kg+enalapril,4 mg/kg;p.o.）.1.2 Study 1 was to investigate the effects of enalapril on pharmacokinetics of metformin.After a single and 7-day dosing,serial blood samples（0.3 mL）of rats were collected at 10,20,40,60,90,120,180,240,360,480 and 600 min,respectively.The plasma concentration of metformin was determined by HPLC.The pharmacokinetic parameters were assessed with non-compartment model.1.3 Study 2 was to investigate the effects of enalapril on tissue uptake of metformin.After a single and 7-day dosing,plasma and tissue samples of rats were collected at 2 h after drug administration,respectively.The blood and tissue concentrations of metformin were determined according HPLC,and the uptake of liver and kidney was calculated.1.4 Study 3 was to evaluate the effects of enalapril on urinary excretion of metformin.After a single and 7-day dosing,urine samples of rats were collected at intervals of 0–2,2–4,4–6,6–8,8–10,10–12 h after drug administration,respectively.The volume of urine was recorded.The concentration of metformin in urine was determined by HPLC.1.5 Study 4 was to evaluate the effects of enalapril on the expression of hepatic and renal transporters related metformin.Rats were orally administrated for 7 days,liver and kidney were collected.The expression of rOCTs and rMATE1 in liver and kidney was evaluated by Western blot analysis.1.6 Study 5 was to evaluate the effects of enalapril on tissue distribution of metformin and biochemical parameters after long-term administration.Blood and tissue samples of rats were collected at 2 h after oral administration for 30 days.The tissue concentrations of metformin were determined according HPLC.Lactic acid（LCA）,urea nitrogen（BUN）,aspartate aminotransferase（AST）,creatinine（Cre）,alanine aminotransferase（ALT）and uric acid（UA）levels were determined using biochemical auto analyzer.2 Effects of telmisartan on pharmacokinetics of metformin in rats2.1 The groups setting of animals and drug administration:a total of 12 rats were randomly divided into control group（metformin,100 mg/kg;p.o.）and co-administration group（metformin,100 mg/kg+telmisartan,8 mg/kg;p.o.）.2.2 Study 1 was to investigate the effects of telmisartan on the pharmacokinetics of metformin.After a single and 7-day dosing,serial blood samples（0.3 mL）of rats were collected at10,20,40,60,90,120,180,240,360,480 and 600 min,respectively.The plasma concentration of metformin was determined by HPLC.The pharmacokinetic parameters were assessed with non-compartment model.2.3 Study 2 was to investigate the effects of telmisartan on tissue distribution and uptake of metformin.After a single and 7-day dosing,plasma and tissue samples of rats were collected at 2h after drug administration.The blood and tissue concentrations of metformin were determined according HPLC,and the uptake of liver,kidney and intestine was calculated.2.4 Study 3 was to evaluate the effects of telmisartan on urinary excretion of metformin.After a single and 7-day dosing,urine samples of rats were collected at intervals of 0–2,2–4,4–6,6–8,8–10,10–12 h after drug administration,respectively.The volume of urine was recorded.The concentration of metformin in urine was determined by HPLC.2.5 Study 4 was to evaluate the effects of telmisartan on the expression of hepatic and renal transporters related metformin.After a single and 7-day dosing,the liver and kidney of rats were collected.The expression of rOCTs and rMATE1 in liver and kidney was evaluated by Western blot analysis.2.6 Study 5 was to evaluate the effects of telmisartan on tissue distribution of metformin and biochemical parameters after long-term administration.Blood and tissue samples were collected at2 h after oral administration for 30 days.The tissue concentrations of metformin were determined according HPLC.The levels of LCA,BUN,AST,Cre,ALT and UA were determined using biochemical auto analyzer.Results1 Effects of enalapril on pharmacokinetics of metformin in ratsAfter a single dose,compared with control group,the plasma concentration of metformin in co-administration group was obviously decreased at 120,180,240,360 and 480 min（p<0.01）,the parameters CL/F and V/F were both obviously increased（p<0.01）,while AUC_0-t and C_maxax were both significantly decreased（p<0.01）.There were no significant differences about the parameter t_1/2,urinary concentration,hepatic and renal K_p of metformin between the two groups after a single dose.After 7-day dosing,compared with control group,the plasma concentration of metformin in co-administration group was obviously decreased at 40,60,90,120 and 240 min（p<0.05）,the parameters CL/F and V/F were both obviously increased（p<0.01）,while AUC_0-t,C_max and t_1/2were all markedly decreased（p<0.05）.There were no obvious differences about the hepatic and renal K_p of metformin in two groups.The urinary concentration of metformin in co-administration group was clearly higher than that in control group（p<0.05）.Compared with control group,the expression of rMATE1 in kidney and liver was obviously increased（p<0.05）,while the level of renal protein rOCT2 was significantly decreased（p<0.05）in co-administration group.However,there were no significant differences in the expression of rOCT1 in liver and kidney between the control group and co-administration group.After long-term administration,compared with control group,the levels of LCA and UA in co-administration group were both markedly decreased（p<0.05）with no obvious statistical differences in serum ALT,AST,BUN and Cre levels.The hepatic,renal and cerebral concentrations of metformin in co-administration group were all clearly lower than those in control group（p<0.05）.2 Effects of telmisartan on pharmacokinetics of metformin in ratsAfter a single dose,compared with control group,the plasma concentration of metformin in co-administration group was obviously increased at 90 and 120 min（p<0.05）,the levels of AUC_0-t,AUC_0-∞,C_max and renal K_p were all obviously increased（p<0.01）,while CL/F and V/F were both significantly decreased（p<0.01）.There were no significant differences about the parameter t_1/2 and urinary concentration of metformin between the two groups.There were no significant differences in the expression of rOCTs and rMATE1 in liver and kidney between the two groups.After 7-day dosing,compared with control group,the plasma concentration of metformin in co-administration group was obviously increased at 40,60,90,120,180,240 and 360 min（p<0.05）,the levels of AUC_0-t,AUC_0-∞,C_maxax and renal K_p were all obviously increased（p<0.05）,while CL/F and V/F were both markedly decreased（p<0.01）.There were no significant differences about the parameter t_1/2 and urinary concentration of metformin between the two groups.Compared with control group,the expression of rOCT1 in liver and kidney as well as rOCT2 in kidney was obviously increased（p<0.05）.However,there were no significant differences in the expression of rMATE1 both in liver and kidney between the control group and co-administration group.After long-term administration,compared with control group,the level of BUN was markedly increased（p<0.01）with no obvious statistical differences in serum ALT,AST,LCA,UA and Cre levels in co-administration group.Compared with control group,the hepatic concentration of metformin was decreased significantly（p<0.05）,while the renal concentration of metformin was obviously increased（p<0.01）in co-administration group.Conclusions1 After 7-day dosing,enalapril significantly decreased the plasma and renal concentrations with no effects on renal K_p of metformin,which could be related to the increased urinary excretion of metformin by inducing the expression of renal rMATE1.Moreover,enalapril markedly attenuated the levels of LCA and UA after long-term administration.2 After a single and 7-day dosing,telmisartan significantly increased the renal K_p of metformin,which might be related to the up-regulated expression of rOCT2 in kidney.In addition,telmisartan significantly increased the level of BUN after long-term co-administration.