Evaluation of an extended-interval gentamicin dosing protocol in neonates ≤ 33 weeks gestational age

Thumbnail Image
Issue Date
Embargo End Date
Thomas, Jennifer
Hale, LaDonna S.

We evaluated a simple, weight-based, extended-interval dosing (EID) gentamicin protocol specifically in neonates with gestational age ≤ 33 weeks, and its impact on sub-therapeutic peaks, elevated troughs, and simplification of dosing and monitoring as compared to a weight-based, multiple daily dose (MDD) protocol.

Methodology. This study evaluated all infants with GA ≤ 33 weeks receiving gentamicin 1-year before EID protocol implementation in Jan 2002, and 1-year after. The MDD protocol used 2.5mg/kg every 8, 12, 18, or 24 hrs based on weight and age groupings. The EID protocol uses 3mg/kg q24 hours if weight < 1500gm and 4mg/kg if weight ≤ 1500gm. Desired trough was ≤ 2.0 mcg/ml and peak was 5 – 12 mcg/ml.

Results. Characteristics were similar for the 123 MDD and 98 EID patients reviewed. The percentage of patients with at least 1 sub-therapeutic peak was lower with EID (7% vs. 20%, p<0.001); however the percentage with at least 1 elevated trough was similar (15% vs. 19%, p=0.219). Average number of peaks and troughs per patient was lower with EID (1.36 ± 0.69 vs. 1.76 ± 1.38, p=0.006 and 1.4. ± 0.77 vs. 1.91 ± 1.45, p=0.001, respectively). Average number of doses administered per day was also lower with EID (1.23 ± 0.70 vs. 1.47 ± 1.20, p=0.016).

Conclusions. In this very premature neonate population, this simple, weight-based, EID gentamicin protocol appeared to provide optimal therapeutic levels requiring fewer serum measurements and fewer doses administered per day as compared to a traditional gestational-age and weight-based, MDD protocol.

Table of Content
A project presented to the Department of Physician Assistant of Wichita State University in partial fulfillment of the requirements for the degree of Master of Physician Assistant.