Objective The aim of this audit was to evaluate the effectiveness of our dosing schedule of 15 mg/kg, at varying intervals depending on corrected age, at achieving trough serum vancomycin concentrations of 10–15 mg/l as standard, or 15–20 mg/l for less sensitive strains of methicillinresistant Staphylococcus aureus.1
Methods The details of all patients receiving vancomycin on our neonatal unit between 1 April 2010 and 31 March 2011 were collected retrospectively from pharmacy Centralised Intravenous Additive Service orders. Data on vancomycin prescribing, therapeutic drug monitoring and dose adjustments were collated from the patients' medical records and biochemistry data, to capture usual practice on our unit.
Results 39 patients were recruited into the audit, but data was only available for 37. The corrected gestational age of patients ranged from 25+5 to 60 weeks and the weight from 0.415 to 7 kg. 71 courses were given, ranging from 3 to 58 doses; a mean of 13.46 doses per patient. 96% were prescribed the correct dose, 85% were written clearly and correctly, 93% were given within 1 h of the prescribed time and 73% of first levels were taken pre third dose. 26% of initial trough levels were 10–15 mg/l; dose adjustments increased this to 60% by the last level taken. 54% of doses were administered when the serum vancomycin trough levels were not in range. The mean number of doses before a serum level was >10 mg/l was 4.96. Analysis of the data shows that patients up to 33 weeks needed 30 mg/kg/day and 33–44 weeks needed 45 mg/kg/day or more. There is not enough data to evaluate patients greater than 44 weeks gestation.
Conclusion Vancomycin is an important glycopeptide antibiotic used to treat Gram positive bacterial infections.1 but it is essential to monitor serum trough levels to enhance efficacy.2 The primary aim was to establish whether our dosing regimen achieves therapeutic vancomycin serum levels. From this data, it can be concluded that a new dosing regimen is required. The proposed schedule is 15 mg/kg/dose 12 hourly if corrected gestation ≤32 weeks, increasing to 8 hourly for 33–44 weeks. Patients with a corrected gestation greater than 44 weeks should then follow the Trust's paediatric vancomycin dosing regimen, which starts at 20 mg/kg 8 hourly. Once an initial dose has been established, it can be seen that further guidance is needed for monitoring and dose alterations.