[Evaluation of three dosage regimens of amikacin using pharmacokinetic models in patients with cystic fibrosis]

Abstract

Background: Once-daily administration of aminoglykosides is routinely used, but comparative efficacy data for patients with cystic fibrosis are not available.

Methods and results: The aim of the this study was to compare the predicted pharmacodynamic (PD) activity of amikacin at 28 mg/kg/den administered every 24 hod.(q24h), q12h, and q8h. Pharmacokinetic (PK) data were derived from analysis of the amikacin serum concentration from 42 CF children patients. Individual pharmacokinetics values were used to construct serum concentration--versus time curves and to determine various indices (c peak/MIC ratio and time during the concentration was less than the MIC--T < MIC) for all three dose regimens described above. MIC (minimal inhibitory concentration) for Pseudomonas aeruginosa was 4 mg/l. Significantly lower c peak/MIC but shorter T < MIC were noted when regimens of q8h versus q12h (p < 0.001), q8h vs. q24h (p < 0.001) and q12h vs. q24h (p < 0.001) were compared. This analysis suggests that the potential advantage of achieving a greater c peak/MIC with once-daily aminoglycoside administration may be neutralized by the significantly greater T < MIC in CF patients compared with that achieved with multiple-daily-dosing regimens.

Conclusions: Routine use of once daily amikacin administration could not be recommended until the clinical data confirming efficiency of this dose modality are available.