Vancomycin is used in pediatric patients usually at 40 mg/kg/day four times daily. Recent data demonstrated the need of large doses to reach therapeutic concentrations in critical patients. Describe dosage regime of vancomycin in patients from a pediatric intensive care unit, register values of plasmatic concentrations and determine the regimes necessary to reach therapeutic troughs. POPULATION, MATERIALS AND METHODS: We made an observational, retrospective study. Patients who received

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... n by more than two days where studied. Patients who didn't register vancomycin troughs (minimum values) and/or with elevated serum creatinine were excluded. The age, grouping in younger than (<) 2 years and older than (>) 2 years and troughs of vancomycin were registered. Volume of distribution (Vd) and half-life (t 1/2) were obtained. Results. We studied 97 patients. Patients with undetectable plasmatic concentrations younger than two years were 14 and the older ones were 9, this difference was not statistically significant (p= 0.063). Mediam of the regime of administration for the younger group was 50 mg/kg/day each 6 h and for the older 40 mg/kg/day four times a day. Mediam (range) of Vd and half-life (t 1/2) for the group of < 2 years and >2 years were 0.682 (0.504-1.06) L/kg, 6.12 (2.66-17.49) h; 0.685 (0.389-1.198) L/kg, 4.88 (3.59-15.4) h, without significant differences. Dosage regime required an increase in frequency, in addition there were no significant differences between pharmacokinetic parameters and final administration regime for both groups, being able to suppose that equal schemes of administration could be implemented more frequently.