Comparison of the fluoroquinolones based on pharmacokinetic and pharmacodynamic parameters

Assessment of pharmacodynamic activity from standard in vitro minimum inhib itory concentrations (MICs) alone is insufficient to predict in vivo potenc y. Achievable serum and tissue concentrations as well as pharmacokinetic ch aracteristics must be considered. When pharmacokinetic and pharmacodynamic values are combined, the area under the inhibitory curve (AUIC) and peak co ncentration:MIC ratio predict clinical cure for fluoroquinolones. Clinical data and animal models indicate that a peak:MIC of 10:1 and above and an AU IC of 125 and above are predictive of a clinical cure for this class of ant imicrobials against gram-negative organisms. The values may be used to comp are and contrast fluoroquinolones to determine which would be best for trea ting a specific microorganism. Pharmacodynamic data also can be used to des ign regimens that minimize the risk of suboptimal drug levels. Ensuring the optimal fluoroquinolone dosage based on pharmacodynamic principles would d iminish the emergence of resistant organisms and prevent treatment failures .