Pharmacokinetics of tobramycin in the newborn.

Following an intramuscular dose of 5.0 mg of tobramycin in eight full-term newborn infants, peak levels averaging 2.69 +/- 0.70 microgram/ml were attained after 30 to 60 minutes. The serum half-life thereafter correlated inversely to postnatal age during the first seven days after birth. Pharmacokinetic analysis revealed that in newborn infants the elimination rate was markedly declined, but the absorption rate was nearly the same as that in older children. Average urinary recovery within eight hours was as low as 26.8%, which suggested accumulation of this antibiotic in the renal tissue.