Abstract
Tobramycin is commonly used in newborn infants but little is known about its pharmacokinetics in identical twins. We studied six infants (gestational age 29-31 weeks; postnatal age 3-4 days; birth weight 1.0-1.3 kg) receiving tobramycin 2.5 mg/kg IV over 20 minutes every 12-18 hours. On third day of therapy, blood samples were collected at 0, 0.5, 1, 2, 4, 8, 12 and 18 hours after starting the infusion and analyzed by EMIT. Peak and trough serum concentrations of tobramycin ranged from 5.3-8.4 μg/ml and 1.2-2.0 μg/ml, respectively. Total clearance (clT) ranged from 0.74-1.19 ml/min/kg, distribution volume (V) from 0.74-0.94 L/kg, and elimination half-life (t½) from 8.2-12.8 hours. Comparison of data between infants in three identical twin pairs showed that despite a similar infusion method: (a) the time to achieve peak serum concentration ranged from 0.5-2.0 hours; (b) the peak and trough concentrations varied from 0-50%; and (c) the clT;, V and t½ varied from 3-20%. These data indicate that peak and trough serum concentrations may be more variable than the kinetic parameters in identical twins. This information should be considered in therapeutic drug monitoring of tobramycin in identical twins during the newborn period.
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Nahata, M., Powell, D. & Miller, M. 402 TOBRAMYCIN PHARMACOKINETICS IN IDENTICAL TWINS DURING NEWBORN PERIOD. Pediatr Res 19, 177 (1985). https://doi.org/10.1203/00006450-198504000-00432
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DOI: https://doi.org/10.1203/00006450-198504000-00432