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

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Thomas, Jennifer
Hale, LaDonna S.
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Gentamicin , Aminoglycosides , Neonates , Daily dosing , Pharmacokinetics in various combinations
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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.

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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.
Wichita State University, Dept. of Physician Assistant
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