Study design and procedures
Information collected following review of the electronic medical record
(EMR) included: baseline demographics, microbiologic data, lung function
data, renal function data, and tobramycin dosing data.
AUC24, Cmax, time undetectable, and all
additional patient-specific pharmacokinetic parameters were calculated
from two post-dose tobramycin serum concentrations using
Excel©-based log-linear regression. Monitoring of
tobramycin within this study typically adhered to our institution
guidelines, which recommend obtaining levels four and ten hours
following doses administered every 24 hours, and two and eight hours
following doses administered every 12 hours. Per institution guidelines,
patients typically had levels obtained after the third day of IV
tobramycin therapy to allow for adequate rehydration. Doses were
adjusted to achieve a target peak concentration of ≥12 mg/L (or eight to
ten-fold the highest PsA MIC) and a trough concentration <0.5
mg/L. Institutional guidelines also recommend increasing the dosing
frequency of IV tobramycin in patients who have a calculated time
undetectable (concentration ≤0.5 mg/L) for longer than 8 hours within a
24-hour dosing interval.