1. Illustration of the concept of peak concentration to the minimum inhibitory concentration (MIC) ratio for aminoglycosides. The MIC for the given organism to gentamicin is 2 mg/L, whereas the tobramycin MIC is 0.5 mg/L. Administration of gentamicin would result in a suboptimal peak:MIC ratio (<10), which could increase the chances for development of resistance or an inadequate response. Administration of tobramycin would result in a peak:MIC ratio of 12, which should improve efficacy. Note that modification of the gentamicin regimen to produce peak serum concentrations of 20 mg/L (42 μmol/L) or more (as commonly done with once-daily administration) also would result in a peak:MIC ratio of ≥10.
Source: Laboratory Tests to Direct Antimicrobial Pharmacotherapy, Pharmacotherapy: A Pathophysiologic Approach, 10e
Citation: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey L. Pharmacotherapy: A Pathophysiologic Approach, 10e; 2017 Available at: Accessed: November 13, 2017
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