Background and importance The practice of routine monitoring and adjusting serum vancomycin drug concentrations is relevant to lessen the potential for nephrotoxicity and ototoxicity and to achieve therapeutic concentrations. However, therapeutic monitoring in paediatric patients is not widely known.

Aim and objectives To describe the clinical and pharmacokinetic parameters in a cohort of paediatric patients treated with vancomycin and to analyse the achievement of the pharmacokinetic objectives after monitoring of vancomycin serum concentrations (SC) and dosage adjustment performed by the hospital pharmacy department.

Material and methods A retrospective study of paediatric patients treated with intravenous vancomycin from 2019 to 2020 was conducted. Variables collected were: sex, age, weight, diagnosis, bacterial isolation, infusion type, initial dosage and dose after two adjustments. Pharmacokinetic parameters were: volume of distribution (Vd), total clearance (Cl), elimination half-life (t_1/2) and 24 hour area under the curve (AUC). Data were expressed as median (range) values.

The goals for vancomycin SC were 15–20 mg/dL trough levels (for intermittent infusion) or 20–25 mg/dL steady state concentrations (for continuous infusion)

Results 32 patients were studied, 62% males, with a median age of 51 months (2 months–16 years) and median weight of 16.5 (5–53) kg. Diagnoses were: catheter related bloodstream infection (n=7), surgical infection (n=7), meningitis (n=3), pneumonia (n=3), osteomyelitis (n=2) and other (n=10). Microorganisms were isolated in 66% of patients: Staphylococcus epidermidis (n=12), Streptococcus spp (n=3), Enterococcus spp (n=2), Staphylococcus aureus (n=1) and other (n=3). 78% of patients were treated initially with intermittent infusion and 22% with continuous infusion. After monitoring, 38% changed from intermittent to continuous infusion.

Median initial dose was 51 (34–80) mg/kg/day, and median doses after the first and second adjustments were 65.5 (40–95) and 68.6 (47–87) mg/kg/day, respectively. Median Vd, Cl, t_1/2 and AUC were 0.82 (0.77–0.91) L/kg, 0.15 (0.06–0.85) L/hour/kg, 3.46 (0.63–15.10) hours and 408 (57.57–958.90) mg×hour/L. 9% of patients did not require dosage adjustment. In the remainder (91%): 45% obtained optimal SC after the first monitoring, 28% after the second monitoring, 20% after subsequent monitoring and 7% discontinued due to another isolation.

Conclusion and relevance Vancomycin was used as target therapy in most cases. The wide use of vancomycin continuous infusion as well as the high doses given were remarkable. Most patients needed dosage adjustments to achieve therapeutic SC and it was possible after the first two pharmacokinetic adjustments.

Conflict of interest No conflict of interest