Individualized aminoglycoside dosage regimens in patients with cystic fibrosis

Individualized dosage regimens have recently been recommended for patients treated with aminoglycoside antibiotics. We have developed a calculator-based program for our patients with cystic fibrosis and have studied 93 courses of intravenous aminoglycoside treatment, comparing predicted and measured values in 45 courses. Pharmacokinetic parameters differed notably among subjects: this was reflected by widely variable total daily aminoglycoside dosage requirements. The mean daily dosage requirements (+/- SD) for tobramycin (62 treatment courses) was 13.0 +/- 3.74 mg/kg, and for gentamicin (26 treatment courses) was 11.5 +/- 2.6 mg/kg. The accuracy of the program was evaluated by its ability to predict peak and trough values in individuals: 84 percent of measured peaks were within 2 micrograms/ml of the predicted level. Nephrotoxicity was observed in one patient, ototoxicity in three. This program provides a simple, safe, and effective method of tailoring an aminoglycoside regimen to the patient's needs.