Monitoring quinolone blood concentrations

Monitoring quinolone (eg ciprofloxacin, moxifloxacin) concentrations can be considered in:

• critically ill patients – significant interpatient pharmacokinetic variability has been reported in these patientsPranger 2011Roggeveen 2022
• patients who have a mycobacterial infection.

Current evidence indicates that reaching target quinolone plasma concentrations is associated with improved pharmacokinetic outcomes in critically ill patientsAbdul-Aziz 2020Abdulla 2022Roggeveen 2022.

For ciprofloxacin, the suggested area under the concentration–time curve over a 24-hour period (AUC₂₄) to minimum inhibitory concentration (MIC) ratio (AUC₂₄/MIC) is more than 125 for gram-negative pathogens and more than 30 for gram-positive pathogens (eg Streptococcus pneumoniae)Abdulla 2022Roggeveen 2022.

The maximum ciprofloxacin plasma concentration (C_max) to MIC ratio (C_max/MIC) may be measured as an alternative to AUC₂₄/MIC. The suggested target C_max/MIC is 8 to 12. The C_max should be taken 30 minutes after the end of the intravenous infusionAbdul-Aziz 2020Ambrose 2001Bhavnani 2008.

There are insufficient data to determine a toxicity threshold for quinolonesAbdul-Aziz 2020Ambrose 2001Bhavnani 2008.

For information on monitoring quinolone concentrations, see the International Association for Therapeutic Drug Monitoring and Clinical Toxicology position paper.