Purpose The objective of this study was to evaluate a standard starting dose of vancomycin and a possible relationship between body mass index (BMI) and plasma levels (therapeutic range 10–15 µg/mL).

Material and methods Retrospective study of samples collected in a tertiary hospital of 413 beds, over a period of 3 years (2012–2014), in patients who were prescribed a standard initial dose of vancomycin 1 g/12 h.

Data collected were: weight, height, gender, age, creatinine plasma levels and vancomycin plasma levels. The collected data were grouped according to BMI (18.5–25=normal weight, 25–30=overweight and >30=obesity) and plasma concentrations of vancomycin. Exclusion criteria were: samples from patients with renal insufficiency (creatinine >1.2 mg/dL) and patients with an initial dose of vancomycin different from the standard dose.

The relationship between plasma levels of vancomycin and BMI was assessed by ANOVA statistical analysis.

Results 114 determinations of plasma levels of vancomycin from different patients were reviewed; 51 normal weight patients, 45 overweight patients and 18 obese patients, with a mean age of 61.27 ± 18.49, 68.46 ± 13.07 and 66.27 ± 13.47 years, respectively.

In the normal weight group, 74.5% were men and 25.5% were women; in overweight group, 73.3% were men and 26.7% were women; and in obesity group, 66.6% were men and 33.3% were women.

Mean (SD) plasma levels of vancomycin in the normal weight group were 13.98 ± 10.61 µg/mL, in the overweight group 13.77 ± 8.32 µg/mL and in the obese group 10.7 ± 4.67 µg/mL.

In the statistical study, we obtained a value distribution F of 1.1669, less than 3.09, a value that should be overcome to have statistical significance (95%).

Conclusion The standard starting dose of 1 g/12 h reaches the therapeutic range in most patients. There was no statistically significant relationship between BMI and mean plasma levels of vancomycin in our study, possibly because of the small sample size.

No conflict of interest.