Pharmacokinetic-based adjustment of individual aminoglycoside dosage
regimens is currently being utilized in the clinical setting in an attempt to avoid toxicity
and/or enhance efficacy. In this report, comparisons have been made between initial and
adjusted aminoglycoside dosage employed in toddlers and older children with cystic fibrosis
or leukemia (high daily dose) and neonates (low daily dose) with suspected or proven
infection. The initial versus adjusted mean aminoglycoside dosage was 14.1 and
17.0 mg/kg/day, respectively, in toddlers and older children with cystic fibrosis, and 7.1
and 11.5 mg/kg/day, respectively, in toddlers and older children with leukemia. Neonates
with suspected or proven infection had an initial mean total daily dose of 7.4 mg/kg/day
and the adjusted mean daily dose was 5.4 mg/kg/day. The use of a single pharmacokinetic
dosing model for all patients, irrespective of evidence of increased or decreased drug elimination,
results in widely differing drug dosages. Important and serious questions must be
considered regarding the balance between efficacy and toxicity resulting from the rigid
manner by which dosage adjustment protocols are employed.