Serum concentrations of gentamicin following oral administration to preterm newborns

Serum gentamicin concentration was measured in 31 newborn babies who received oral gentamicin for prophylaxis of necrotizing enterocolitis in order to determine the presence and degree of gastrointestinal absorption and its relationship to birth weight, gestational age, postnatal age and perinatal asphyxia. A dose of 2.5 mg/kg every 6 h by nasogastric tube was administered during a 3-week course after birth. The mean birth weight was 1,269 +/- 489 g; mean gestational age 29.6 +/- 3.7 weeks. The mean serum gentamicin levels were: 0.06 +/- 0.03 microgram/ml at 30 min after the first dose; 0.29 +/- 0.48 microgram/ml at 4 h; 1.62 +/- 1.43 microgram/ml at 24 h, and 0.33 +/- 0.57 microgram/ml at 7 days. The 24-hour and 7-day samples were taken before the next dose. The mean 24-hour level was significantly (p less than 0.001) higher than the other levels. There was no significant (p less than 0.05) relationship between the 24-hour serum gentamicin level and birth weight, gestational age or umbilical venous pH.