Background Although vancomycin dosing recommendations are based on creatinine clearance estimated using the Cockcroft–Gault formula, it may not be optimal for critically ill patients due to their physiologic changes. A direct measure of creatinine clearance can provide more accurate information on renal function and dose adjustment of vancomycin.

Purpose The objective of the current study was to determine vancomycin clearance during intermittent infusion and to explore its correlations with measured and estimated creatinine clearance in critically ill patients with normal renal function.

Material and methods 20 critically ill patients who received treatment with vancomycin intermittent infusion were enrolled (16 men, 4 women, age 46.8±19.8 years, body mass index 24.0±2.8 kg/m², estimated glomerular filtration rate (eGFR) 108.0±44.3 mL/min, Acute Physiology and Chronic Health Evaluation (APACHE) II score 12.7±5.0 at admission). Vancomycin clearance (CL_van) was determined 1–2 times for each patient during the study (n=32). Its correlation with measured creatinine clearance in 6 hour urine (CL_6-h) and estimated creatinine clearance from the Cockcroft–Gault formula (CL_CG) was investigated.

Results Data analysis revealed that CL_6-h was a stronger predictor of CL_van rather than CL_CG (Pearson coefficient correlation=0.83 vs 0.67; p<0.001). The relationship between CL_van and CL_6-h was utilised to develop the following equation to estimate clearance of vancomycin in the critically ill patients without renal impairment: CL_van (mL/min)=26.55+0.73 CL_6-h ( mL/min).

Conclusion Measured creatinine clearance estimated from a 6 hour urine collection is a simple test that provides more reliable and practical information compared with the Cockcroft–Gault formula for vancomycin dose adjustment in critically ill patients with normal renal function.

References and/or acknowledgements We would like to acknowledge all of the patients who agreed to contribute to the study.

No conflict of interest