Evaluation of Treatment Courses When Vancomycin Is Given Every 8 Hours in Adult Patients.

Background: Several nomograms include recommendations to give intravenous (IV) vancomycin at 8-hour dosing intervals (Q8H). However, there is a lack of detailed data regarding this dosing recommendation.

Methods: A retrospective chart review of 100 patients who received 107 treatment courses of vancomycin Q8H for at least 5 days was performed. Distribution of vancomycin trough levels and rate of nephrotoxicity were evaluated.

Results: Median patient age was 38 years (interquartile range [IQR] 27-50 years), median weight was 67 kg (IQR 55-79 kg), and median creatinine clearance was 124 mL/min (IQR 101-147 mL/min). Median duration of Q8H dosing was 9 days (IQR 7-12 days). Within the initial 96 hours, only 7% (7 of 104) of maximum trough concentrations were >20 mg/L (median dose 15 mg/kg [IQR 15-18 mg/kg]). After 96 hours of Q8H dosing, 34% (30 of 89) of maximum troughs were >20 mg/L (median dose 17 mg/kg [IQR 15-20 mg/kg]), P = .0005. The rate of nephrotoxicity was 4%.

Conclusion: We observed an increase in the percentage of trough levels >20 mg/L later during treatment courses of vancomycin IV Q8H with a relatively small corresponding increase in vancomycin dose. Close monitoring of trough levels (eg, every 3 days) with prolonged courses of vancomycin IV Q8H is warranted.