P02 An audit of vancomycin dosing in the neonatal units
Authors: Penny Fletcher , Shruti Patel 
Published: January 2018

Aim

To audit the prescribing and monitoring of vancomycin in the neonatal units against the local guideline.

The neonatal vancomycin guideline has never been audited. Anecdotally, prescribing and monitoring of this drug is challenging, with pharmacists frequently being asked for advice. The guideline has two ranges depending on which bacteria are being treated, 10–15 mg/L and 15–20 mg/L.

The initial dosing frequency is different for babies greater than 10 days of age.

Method

Data on vancomycin doses, levels, time taken, patient age, weight and renal function, were collected on a data collection form prospectively, from prescriptions and clinical records for all babies on vancomycin on between 17/10/2016 and 16/12/2016. Patients were followed throughout their stay; some had repeated courses. The audit was approved locally. Audit standards were derived from the guideline, with 100% adherence aimed for.

Data were entered onto an Excel spreadsheet.

Results

Data was collected from 19 patients, 28 vancomycin courses and 31 vancomycin levels.

28/28 (100%) prescriptions had the correct initial dose. In one neonate the dose changed from 12 to 8 hourly when they were 10 days old. This change led to a high level.

13/15 (87%) had the level taken at the correct time. Two were taken 2–3 hours late. Thirteen courses were stopped before requiring levels.

19/31 levels (62%) were within a safe range (10–20 mg/L).

All 6 levels>20 mg/L had the next dose held and the level repeated. In two of these cases there was no subsequent dose reduction causing further high levels. In one case a further vancomycin course was prescribed as per guidelines, with no consideration of previous levels, a high level was recorded again.

Two levels between 15–20 mg/L were considered too high; a dose was omitted, resulting in two sub-therapeutic levels (below 10 mg/L).

Of the other four low levels, three were not acted upon appropriately – no dose or frequency increase, one was acted on correctly with a dose increase.

Conclusion

The size of the data set was small but the descriptive findings are interesting.

The initial aspects of the guideline are adhered to with all doses prescribed correctly. High levels resulted in doses being held and levels repeated but subsequent actions were suboptimal. Levels appeared to be viewed in isolation and so either no change or an incorrect change was made causing further avoidable high levels. Often low levels were not acted upon appropriately.

It is possible that there is limited understanding of pharmacokinetic principles underpinning the adjustment of doses.

Changes have been made to the guidelines including a statement that the doses are the initial starting doses only and that dose adjustments are based on levels not age. The different ranges caused confusion and given that the specific bacteria presentmay not be known when initiating treatment, the guidelines have been amended to clarify the safe range of vancomycin to be 10–20 mg/L. Teaching sessions with worked examples will be held with all prescribers and nursing staff.