Evaluating the duration of post-discontinuation therapeutic ampicillin exposures in preterm infants.

OBJECTIVE: Determine if preterm infants have prolonged therapeutic post-discontinuation antibiotic exposures (PDAE) following empiric ampicillin. STUDY DESIGN: Prospective study of 27 infants ≤7 days and <37 weeks gestational age (GA) receiving ampicillin (200 mg/kg/day); 49 post-discontinuation PK samples were collected. Exposures were predicted using PK simulations and a prior ampicillin PK model. The probability of target attainment 24- and 36-h after the final ampicillin dose for various minimum inhibitory concentrations (MICs) and the duration of therapeutic PDAE was calculated. RESULT: At 24- and 36-h after ampicillin, the probability of exposures ≥1 μg/mL was 95% and 60%, respectively. PDAE (≥1 μg/mL) lasted a median 33 h (95% confidence interval: 15, 79), and varied with GA, from median 53 h (<28 weeks GA) to 27 h (34-36 weeks GA). CONCLUSION: Many preterm infants experience therapeutic exposures at least 24 h after the final ampicillin dose. Shorter courses could be considered.

Duke Scholars

Author Daniel Kelly Benjamin Jr. Pediatrics, Infectious Diseases

Author Kanecia Obie Zimmerman Pediatrics, Critical Care Medicine

Author Rachel Gottron Greenberg Pediatrics, Neonatology

Author Daniel Gonzalez Medicine, Clinical Pharmacology

Author Michael Cohen-Wolkowiez Pediatrics, Infectious Diseases

Author Angelique Boutzoukas Pediatrics, Infectious Diseases