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.(q24 h), q12 h, and q8 h. Pharmacokinetic (PK) data were derived from analysis of the amikacin serumconcentration from42 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 theMIC – T

        Key words: cystic fibrosis, amikacin, pharmacokinetic parameters, MIC.