Ciprofloxacin vs Levofloxacin MIC and PK/PD

We aim to clarify a practical question for hospitals - when should clinicians use ciprofloxacin and when should levofloxacin be preferred? Both drugs are used for similar Gram-negative infections but decisions are often based on habit rather than on a clear understanding of how likely each drug is to hit pharmacodynamic targets at real-world doses.

Using isolate-level data from the Pfizer ATLAS programme, we will focus on bacteria that have been tested against both ciprofloxacin and levofloxacin. For these isolates we will combine MIC data data with published pharmacokinetic models and run Monte Carlo simulations for commonly used regimens. For each organism and MIC we will estimate the probability that each regimen achieves recognised exposure targets for serious Gram-negative infection.

By making fluoroquinolone choices more rational, this work should reduce treatment failure, shorten admission and limit unnecessary toxicity.