P27 Impact of new vancomycin dosing and monitoring guideline
Authors: Judith Martin , David Sharpe , Katie Duckers 
Published: January 2018

The Neonatal and Paediatric Pharmacists Group (NPPG) released a report which carried out a vancomycin in paediatric audit (VIPA). This report reviewed the effectiveness of currently employed intravenous vancomycin dosing regimens. It stated that British National Formulary for Children (BNFC) vancomycin dosing was not sufficient for achieving the target therapeutic range in typical patients and higher, more frequent dosing is required to reach target levels quicker.1,2

Based on this report, we amended our dosing guidelines to the following empirical starting doses for children with normal or mildly impaired renal function:

Infant 1–6 months: 10 mg/kg 6 hourly

Infant > 6 month: 15 mg/kg 6 hourly

To evaluate if the new guidelines achieve target therapeutic levels quicker without increasing toxicity or incidence of adverse effects an audit was carried out. The results were then compared to an audit carried out in 2009 using the old vancomycin pathway which based doses on BNFC dosing of 15 mg/kg every eight hours.3

The main objectives were to determine the number of patients that achieved target therapeutic range at steady state, and the dose required to achieve this, the time taken to achieve target therapeutic range, the number of patients that achieved levels <10 mg/L (sub-therapeutic) and >20 mg/L (toxic) and the frequency of adverse effects.

Method

Data was collected for all patients who had been started on vancomycin from 14th September 2016 to 5th December 2016. Using our electronic prescribing system, a daily report identified patients who had vancomycin prescribed. The data collected was compared to the data collected from the 2009 audit.

Results

23 patients had been commenced on vancomycin during the audit time frame. 20 of these patients (87%) were started on the correct frequency of 6 hourly dosing, and 13 of these patients (65%) were started on the correct frequency and dose of 15 mg/kg/dose.

Of the 13 patients started on the correct dose and frequency, only 6 patients (46%) had their first level taken at the correct time. 4 of these patients (67%) achieved the therapeutic target range of 10–15 mg/L. This has improved from 2009, when an audit completed on the old guidelines showed that 1 patient (7%) reached therapeutic levels without having to adjust dose.

No patients’ reached a trough level greater than 20 mg/L and additionally no patients’ had a 50% or greater increase of serum creatinine, suggesting the change to guidelines does not negatively impact on toxicity or acute kidney risk.

The mean time to achieve therapeutic dose has decreased from 3.6 days in 2009 to 1.4 days in 2016.

There was a correlation between age and vancomycin levels-with the average level for patients between 1–6 months being 10.67 mg/L (therapeutic). Whereas the average vancomycin level for patients over 6 months was 8.14 mg/L (sub- therapeutic). This suggests the new guidelines are more effective for the lower age range group.

Conclusion

The new guidelines have helped to achieve target levels quicker, with no increase in toxicity. However, there are still areas for improvement for older paediatric patients; reinforcing the idea of aged based dosing.

References

Cole C, Shepard M. A review of the trust’s paediatric vancomycin guidelines. Neonatal and Paediatric Pharmacists Group2015;1(1):46. http://adc.bmj.com/content/100/6/e1.50 [Accessed: 22nd August 2016].

Nash C, Gooding N, Muller H. Intermittent intravenous vancomycin in children aged over 1 month: Empirical dosing for optimum trough levels. Report to the Neonatal and Paediatric Pharmacist Group January 2016 Neonatal and Paediatric Pharmacists Group2016;1–40. [Accessed: 2nd September 2016].

British National Formulary. 2014th–5th ed. BMJ group, Pharmaceutical Press 2015. [Accessed: 2nd September 2016].