title: 'Old' antibiotics for emerging multidrug-resistant bacteria.
abstract: OBJECTIVE
  Increased emergence of bacterial resistance and the decline in newly developed antibiotics have necessitated the reintroduction of previously abandoned antimicrobial agents active against multidrug-resistant bacteria. Having never been subjected to contemporary drug development procedures, these 'old' antibiotics require redevelopment in order to optimize therapy. This review focuses on colistin as an exemplar of a successful redevelopment process and briefly discusses two other old antibiotics, fusidic acid and fosfomycin.
  
  
  RESULTS
  Redevelopment of colistin led to an improved understanding of its chemistry, pharmacokinetics and pharmacodynamics, enabling important steps towards optimizing its clinical use in different patient populations. A scientifically based dosing algorithm was developed for critically ill patients, including those with renal impairment. As nephrotoxicity is a dose-limiting adverse event of colistin, rational combination therapy with other antibiotics needs to be investigated.
  
  
  CONCLUSIONS
  The example of colistin demonstrated that state-of-the-art analytical, microbiological and pharmacokinetic/pharmacodynamic methods can facilitate optimized use of 'old' antibiotics in the clinic. Similar methods are now being applied to fosfomycin and fusidic acid in order to optimize therapy. To improve and preserve the usefulness of these antibiotics rational approaches for redevelopment need to be followed.
authors.affiliation: Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Melbourne, Australia.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Bergen
authors.forename: Cornelia B
authors.initials: CB
authors.lastname: Landersdorfer
authors.forename: Hee Ji
authors.initials: HJ
authors.lastname: Lee
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Roger L
authors.initials: RL
authors.lastname: Nation
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000188:drug therapy* / Q000382:microbiology*; D003091:Colistin / Q000009:adverse effects / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016638:Critical Illness; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans
chemical_list: D000900:Anti-Bacterial Agents; D003091:Colistin