Arbeter A M, Saccar C L, Eisner S, Sarni E, Yaffe S J
J Pediatr. 1983 Jul;103(1):131-5. doi: 10.1016/s0022-3476(83)80799-9.
The elimination pharmacokinetics of tobramycin sulfate was studied in 25 newborn infants of birth weight 0.7 to 4.7 kg during 31 treatment episodes. The peak serum concentrations after a 2.5 mg/kg dose were usually within the therapeutic range of 5 to 10 micrograms/ml; however, the serum predose trough values were elevated above the theoretical safe limit of 2 micrograms/ml. Because of the prolonged serum elimination half-lives, a calculated extended dosage interval, sometimes greater than 24 hours, was necessary to obtain a predose trough of less than or equal to 2 micrograms/ml. The serum elimination half-lives inversely correlated with gestational age, extrauterine age, birth weight, and creatinine clearance. The very low ratio of tobramycin renal clearance to creatinine renal clearance was virtually constant and indicated a probable tubular reabsorption of tobramycin. A general dosage schedule based on birth weight was derived from the data. An alternative formula was derived to enable prediction of the tobramycin elimination half-life based on a combination of birth weight, gestational age, and extrauterine age for an infant younger than 7 days of age.
