Does the dose matter?

Clin Infect Dis. 2001 Sep 15;33 Suppl 3:S233-7. doi: 10.1086/321854.


Pharmacokinetic/pharmacodynamic (PK/PD) parameters, such as the ratio of peak to minimum inhibitory concentration (peak/MIC ratio), ratio of 24-hour area under the curve to MIC (24-h AUC/MIC ratio), and the time above MIC, are good indicators of the drug dose-organism interaction. Time above the MIC is the important determinant of the activity of beta-lactams, macrolides, clindamycin, and linezolid. Free drug serum levels of these drugs should be above the MIC for at least 40%-50% of the dosing interval to produce adequate clinical and microbiological efficacy. Peak/MIC and 24-h AUC/MIC ratios are major determinants of the activity of aminoglycosides and fluoroquinolones. In general, peak/MIC ratios should exceed 8 and 24-h AUC/MIC values should be >100 to successfully treat gram-negative bacillary infections and to prevent the emergence of resistant organisms during therapy. The successful treatment of pneumococcal infections with fluoroquinolones and azithromycin appear to require 24-h AUC/MIC ratios of only 25-35. Mutation prevention concentrations are being reported for various fluoroquinolones with different pathogens, but their clinical significance has not yet been established. More information is needed on the role of PK/PD parameters and their magnitude for preventing mutations and the emergence of resistant organisms for most classes of antibiotics.

Publication types

  • Review

MeSH terms

  • Animals
  • Dose-Response Relationship, Drug*
  • Drug Resistance, Bacterial
  • Humans
  • Microbial Sensitivity Tests
  • Mutagenesis / drug effects