Fluctuating antibiotic concentrations are sometimes more desirable than steady concentrations.

• A. False
• B. Not applicable
• C. Depends on antibiotic
• D. True

Answer: (D)

Pharmacodynamics shows that how effectively an antibiotic works depends on the relationship between drug concentration and the pathogen’s MIC. For concentration-dependent killers, higher peaks relative to MIC produce more rapid and extensive bacterial kill, and the presence of a post-antibiotic effect means bacteria stay suppressed even as levels fall. In such cases, dosing strategies that create high peaks with lower troughs can maximize effect while limiting toxicity. Conversely, for time-dependent killers, keeping concentrations above MIC for as long as possible is preferred, which favors steadier exposure. Because there are real scenarios where fluctuating levels improve outcomes, the statement is true.