Background Manufacturers of vancomycin recommend initial dose adjustment based on actual body weight (30–50 mg/kg/day) in patients with normal renal function. Most consensus guidelines recommend 15–20 mg/kg c/8–12 hours, doses that have been associated with plasma concentrations of 15–20 µg/mL, which is the goal in most patients.

Purpose This study evaluated if initial doses were adapted to dosage recommendations, and correlated them with trough concentrations after administrating four doses.

Material and methods A retrospective observational study was conducted from 2 February 2016 to 15 April 2016. The study variables were demographics (sex, age, weight and height), clinical (diagnostic, creatinine clearance), pharmacokinetics (plasma concentration of vancomycin) and pharmacological (regimen). The databases used were the electronic prescribing programme and clinical hospital station.

Results We recruited 38 patients (39.5% men, 60.5% women) with a mean age of 63 years, weight 73 kg and height 165 cm. The percentage of patients who belonged to traumatology was 54.08%, to neurosurgery 27.33%, to haematology 10.52%, to infectious 2.7%, to neurology 2.7% and to pneumology 2.7%. 21% of patients had a creatinine clearance (calculated using the Cockcroft–Gault and edited by body surface area) of >120 mL/min/1.73m², 76.3% of 120–60 mL/min/1.73m² and 2.7% of 59–30 mL/min/1.73m₂. 42.1% of patients began treatment with targeted therapy and 57.9% with empirical. 72% of patients started with 1000 mg/12 hours, 15.6% with 1000 mg/8 hours, 2.7% with 1400 mg/12 hours, 2.7% with 500 mg/8 hours and 7% with 1250 mg/12 hours. 60.5% of patients received an initial dose below 30 mg/kg/day (mean 22.25 mg/kg/day) and 39.5% received an initial dose above 30 mg/kg/day (mean 36.52 mg/kg/day). None of the patients received more than 50 mg/kg/day). 50% of patients had a plasma concentration after 4 doses below 10 µg/mL (mean 7.25 µg/mL), 23.7% obtained concentrations between 10 to 14.9 µg/mL (mean 12.33 µg/mL), 15.8% obtained concentrations between 15 and 20 µg/mL (mean 16.57 µg/mL) and 10.5% had a higher concentration of 20 µg/mL (mean 28.1 µg/mL).

Conclusion Most patients received a lower dose than the actual weight based recommendations and therefore these patients could not reach the concentrations indicated. In conclusion, this would require hospital pharmacists suggesting the appropriate dose for each patient based on their actual weight.

No conflict of interest