Study objectives: To assess the reliability of the intraosseous route of administration for delivery of a loading dose of broad-spectrum antibiotics in a pediatric animal model.
Design: Serum levels achieved within 90 minutes of equivalent intraosseous (IO) and IV bolus dosing of ceftriaxone, cefotaxime, and a combination of ampicillin and gentamicin were compared in the weanling pig.
Subjects: Twelve female weanling pigs were studied in the Animal Facilities Laboratory at the University of Mississippi Medical Center.
Interventions: Through a proximal tibial IO catheter, each anesthetized animal received one of the following: 50 mg/kg ceftriaxone, 50 mg/kg cefotaxime, or 300 mg/kg ampicillin followed immediately by 2.5 mg/kg gentamicin. Venous blood was obtained for antibiotic assay at 15, 30, 45, 60, and 90 minutes after IO injection. The animals were allowed to recover, and, after a one-week washout period, each received the same antibiotic and dose as before through a peripheral IV. Levels were assayed at the same intervals and IO versus IV were compared.
Measurements and main results: Comparable serum levels of all four antibiotics were achieved by the two routes. Gentamicin levels were statistically indistinguishable IO versus IV at all assay intervals. Ampicillin and cefotaxime levels achieved by the two routes were equivalent within one hour of dosing. Serum levels of ceftriaxone after IO administration paralleled those after IV dosing but remained significantly lower at all time intervals.
Conclusions: In the weanling pig model, the IO route was used to deliver serum levels of broad-spectrum antibiotics comparable to those attained after IV administration. The data support the use of standard parenteral doses for IO administration. To overcome potential avid protein binding of ceftriaxone in the bone marrow, we recommend using ceftriaxone at its highest recommended IO loading dose. Consistent with many other medications that have been similarly tested, these data indicate that initial or empiric antibiotic coverage in hypodynamic and shock states in infants and young children need not await the establishment of traditional IV access.