Background and importance Because of the difficulty in achieving target serum concentrations of vancomycin in neonates after the first dose, the pharmacy and the paediatric services developed a new protocol to establish the initial dosage of vancomycin in neonates. To improve efficacy and/or reduce toxicity, therapeutic drug monitoring (TDM) of vancomycin can be used to adapt doses and personalise treatment.

Aim and objectives To assess the rate of implementation of a hospital internal protocol for vancomycin dosage in neonates and the rate of under- and over-dose after the first control of serum concentrations of vancomycin.

Material and methods A retrospective observational study was carried out including all neonates (n=83) who received vancomycin since approval of the protocol (April 2016) to September 2019. According to the new protocol, the dosage of vancomycin is based on gestational age, postnatal age and weight: in patients <29 weeks, the recommended dose was 10 mg/kg/12 hours for neonates <14 days and 10 mg/kg/8 hours for those >14 days; between 30 and 36 weeks, 10 mg/kg/8 hours for neonates <14 days and 12 mg/kg/8 hours for those >14 days. Vancomycin TDM was done before the third dose. For this study, we wanted a trough concentration of 7.5–15 µg/mL.

Results Eighty-three patients with 87 first determinations of vancomycin were included: 45 males and 35 females with an average weight of 1.32 kg (0.53–4.32). The protocol for the initial dosage of vancomycin was followed in 71 (85.5%) patients. Thirty patients (36.4%) presented trough concentrations <7.5 µg/mL, 6 patients (7.2%) had trough concentrations >15 µg/mL and 51 patients (61.4%) had trough concentrations within the target range (7.5–15 µg/mL).

Conclusion and relevance Most of our patients received the dose of vancomycin following the protocol, achieving target concentrations in 61% of determinations. After implementation of the protocol, a minority of patients (7.2%) showed levels higher than the target therapeutic range.

References and/or acknowledgements Thanks to my service for your unconditional support.

No conflict of interest.