Objective Cefditoren,a third-generation cephalosporin antibiotics,has been used in clinic extensively.Whether Mrp2 or other canalicular transporters such as Bcrp and P-gp are involved in the biliary excretion of cefdi...Objective Cefditoren,a third-generation cephalosporin antibiotics,has been used in clinic extensively.Whether Mrp2 or other canalicular transporters such as Bcrp and P-gp are involved in the biliary excretion of cefditoren is unknown.This study is performed to investigate the role of the canalicular transporters in the biliary excretion of cefditoren and the effect of cefditoren on expression levels of some hepatic transporters.Methods We examined the hepatobiliary disposition of cefditoren using probenecid,novobiocin and verapamil as the inhibitors of Mrp2,Bcrp and P-gp respectively in perfused rat livers.The concentration of cefditoren in the perfusate and bile were determined by RP-HPLC with ultraviolet detection at 295nm using a mobile phase composed of 0.1% ammonium acetate-methanol(65∶35).We also investigated the effects of cefditoren on expression of hepatic transporters.The change in mRNA of main canalicular transporters was investigated by RT-PCR and Western blot after administration of cefditoren.Results The values for the hepatic extraction ratio did not change,whereas cumulative biliary excretion rates of cefditoren were significantly reduced to 43.78% and 79.52% over 25 min in the perfused probenecid and novobiocin rats,respectively.After oral administration of cefditoren,the expression levels of Mrp2,Bcrp,Oat2 mRNA were markedly up-regulated,while Mdr1a and Oct1 mRNA were down-regulated by RT-PCR.In concordance with RT-PCR results,Mrp2 expression level was up-regulated by Western blot.Conclusions Mrp2 and Bcrp mediated the biliary excretion of cefditoren,whereas P-gp had no contribution to the transportation of cefditoren into bile.The expression levels of Mrp2,Bcrp and Oat2 mRNA were up-regulated and the expression levels of Mdr1a and Oct1 mRNA were down-regulated by cefditoren.These results provide important data for drug-drug interaction.展开更多
The relationship between pharmacokinetics and pharmacodynamics is a key instrument to improve antimicrobial stewardship and should be aimed to identification of the drug exposure measure that is closely associated not...The relationship between pharmacokinetics and pharmacodynamics is a key instrument to improve antimicrobial stewardship and should be aimed to identification of the drug exposure measure that is closely associated not only with the ability to kill organisms but also to suppress the emergence of resistant subpopulations. This article reviews published studies for efficacy prediction with cefditoren and those aimed to explore its potential for countering resistance spread, focusing on the three most prevalent community-acquired isolates from respiratory infections: Streptococcus pneumoniae(S. pneumoniae), Haemophilus influenzae(H. influenzae) and Streptococcus pyogenes(S. pyogenes). Studies for efficacy prediction include in vitro pharmacodynamic simulations(using physiological concentrations of human albumin) and mice models(taking advantage of the same protein binding rate in mice and humans) to determine the value of the pharmacodynamic indices predicting efficacy, and Monte Carlo simulations to explore population pharmacodynamic coverage, as weapons for establishing breakpoints. Studies exploring the potential of cefditoren(free concentrations obtained with 400 mg cefditoren bid administration) for countering spread of resistance showed itscapability for countering(1) intra-strain spread of resistance linked to fts I gene mutations in H. influenzae;(2) the spread of H. influenzae resistant strains(with fts I gene mutations) in multi-strain H. influenzae niches or of S. pneumoniae strains with multiple resistance traits in multi-strain S. pneumoniae niches; and(3) for overcoming indirect pathogenicity linked to β-lactamase production by H. influenzae that protects S. pyogenes in multibacterial niches. This revision evidences the ecological potential for cefditoren(countering resistance spread among human-adapted commensals) and its adequate pharmacodynamic coverage of respiratory pathogens(including those resistant to previous oral compounds) producing community-acquired infections.展开更多
文摘Objective Cefditoren,a third-generation cephalosporin antibiotics,has been used in clinic extensively.Whether Mrp2 or other canalicular transporters such as Bcrp and P-gp are involved in the biliary excretion of cefditoren is unknown.This study is performed to investigate the role of the canalicular transporters in the biliary excretion of cefditoren and the effect of cefditoren on expression levels of some hepatic transporters.Methods We examined the hepatobiliary disposition of cefditoren using probenecid,novobiocin and verapamil as the inhibitors of Mrp2,Bcrp and P-gp respectively in perfused rat livers.The concentration of cefditoren in the perfusate and bile were determined by RP-HPLC with ultraviolet detection at 295nm using a mobile phase composed of 0.1% ammonium acetate-methanol(65∶35).We also investigated the effects of cefditoren on expression of hepatic transporters.The change in mRNA of main canalicular transporters was investigated by RT-PCR and Western blot after administration of cefditoren.Results The values for the hepatic extraction ratio did not change,whereas cumulative biliary excretion rates of cefditoren were significantly reduced to 43.78% and 79.52% over 25 min in the perfused probenecid and novobiocin rats,respectively.After oral administration of cefditoren,the expression levels of Mrp2,Bcrp,Oat2 mRNA were markedly up-regulated,while Mdr1a and Oct1 mRNA were down-regulated by RT-PCR.In concordance with RT-PCR results,Mrp2 expression level was up-regulated by Western blot.Conclusions Mrp2 and Bcrp mediated the biliary excretion of cefditoren,whereas P-gp had no contribution to the transportation of cefditoren into bile.The expression levels of Mrp2,Bcrp and Oat2 mRNA were up-regulated and the expression levels of Mdr1a and Oct1 mRNA were down-regulated by cefditoren.These results provide important data for drug-drug interaction.
文摘The relationship between pharmacokinetics and pharmacodynamics is a key instrument to improve antimicrobial stewardship and should be aimed to identification of the drug exposure measure that is closely associated not only with the ability to kill organisms but also to suppress the emergence of resistant subpopulations. This article reviews published studies for efficacy prediction with cefditoren and those aimed to explore its potential for countering resistance spread, focusing on the three most prevalent community-acquired isolates from respiratory infections: Streptococcus pneumoniae(S. pneumoniae), Haemophilus influenzae(H. influenzae) and Streptococcus pyogenes(S. pyogenes). Studies for efficacy prediction include in vitro pharmacodynamic simulations(using physiological concentrations of human albumin) and mice models(taking advantage of the same protein binding rate in mice and humans) to determine the value of the pharmacodynamic indices predicting efficacy, and Monte Carlo simulations to explore population pharmacodynamic coverage, as weapons for establishing breakpoints. Studies exploring the potential of cefditoren(free concentrations obtained with 400 mg cefditoren bid administration) for countering spread of resistance showed itscapability for countering(1) intra-strain spread of resistance linked to fts I gene mutations in H. influenzae;(2) the spread of H. influenzae resistant strains(with fts I gene mutations) in multi-strain H. influenzae niches or of S. pneumoniae strains with multiple resistance traits in multi-strain S. pneumoniae niches; and(3) for overcoming indirect pathogenicity linked to β-lactamase production by H. influenzae that protects S. pyogenes in multibacterial niches. This revision evidences the ecological potential for cefditoren(countering resistance spread among human-adapted commensals) and its adequate pharmacodynamic coverage of respiratory pathogens(including those resistant to previous oral compounds) producing community-acquired infections.
