title: Pharmacokinetic/pharmacodynamic modeling of in vitro activity of azithromycin against four different bacterial strains.
abstract: The bacterial time-kill curves of azithromycin against four bacterial strains (Streptococcus pneumoniae/penicillin-intermediate, S. pneumoniae/penicillin-sensitive, Haemophilus influenzae and Moraxella catarrhalis) were determined by in vitro infection models. Eighteen different pharmacokinetic/pharmacodynamic models were fitted to the time-kill data using non-linear regression and compared for best fit. A simple, widely used E(max) model was not sufficient to describe the pharmacodynamic effects for the four bacterial strains. Appropriate models that gave good curve fits included additional terms for saturation of the number of bacteria (N(max)), delay in the initial bacterial growth phase and/or the onset of anti-infective activity (1-exp(-zt)) as well as a Hill factor (h) that captures the steepness of the concentration-response profile. Azithromycin was highly effective against S. pneumoniae strains and M. catarrhalis while the efficacy against H. influenzae was poor. Applications of these pharmacokinetic/pharmacodynamic models will eventually provide a tool for rational antibiotic dosing regimen decisions.
authors.affiliation: Department of Pharmacy, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Wanchai
authors.initials: W
authors.lastname: Treyaprasert
authors.forename: Stephan
authors.initials: S
authors.lastname: Schmidt
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Rand
authors.forename: Uthai
authors.initials: U
authors.lastname: Suvanakoot
authors.forename: Hartmut
authors.initials: H
authors.lastname: Derendorf
mesh_terms: D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*; D017963:Azithromycin / Q000493:pharmacokinetics* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D004917:Erythromycin / Q000494:pharmacology; D006192:Haemophilus Infections / Q000188:drug therapy; D006193:Haemophilus influenzae / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D001936:Moraxella catarrhalis / Q000187:drug effects; D045828:Moraxellaceae Infections / Q000188:drug therapy; D010403:Penicillin Resistance; D011008:Pneumococcal Infections / Q000188:drug therapy; D013296:Streptococcus pneumoniae / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin; D017963:Azithromycin