Timing of the first vancomycin maintenance dose in an acute hospital setting - room for improvement?

Carruthers, Andrew and Thomson, Alison H. and Semple, Yvonne and Rodger, Rachael (2016) Timing of the first vancomycin maintenance dose in an acute hospital setting - room for improvement? Journal of Medicines Optimisation, 2 (3). pp. 51-55. ISSN 2396-8613

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    Abstract

    Introduction Intravenous vancomycin therapy typically starts with a loading dose followed by a maintenance dose 12 to 24 hours later. In the acute hospital setting, this often results in doses being administered in the middle of the night, which is impractical for both patients and staff. This audit examined current practice and developed new guidelines to support greater flexibility in the timing of the first maintenance dose. Methods Data recording forms used by pharmacists to support the therapeutic drug monitoring of vancomycin were collected from two hospital sites over six weeks. Forms containing at least two vancomycin concentrations were selected and the time of administration of the first maintenance dose was recorded. Individual vancomycin pharmacokinetic parameter estimates were obtained using MAP Bayesian analysis then used to predict vancomycin concentrations 6, 8, 10, 12 and 14 hours after a banded loading dose and 20 mg/kg (capped at 3000 mg). Predicted concentrations were compared with a target range of 10 – 20 mg/L. Results Data were obtained from 49 patients with a mean (SD) age of 63.1 (16.7) years and weight 80.1 (27.6) kg. In all patients, creatinine clearance estimates were >40 mL/min and, according to current practice guidelines, all patients required 12 hourly maintenance dosing. The time recorded for the administration of the first maintenance dose was between 11 pm and 7 am in 30 (61%) of these patients. In 14 patients (29%), the first maintenance dose was administered >12 hours after loading. The target range was achieved with banded doses (20 mg/kg) in 65% (71%) of concentrations at 6 hours, 74% (84%) at 8 hours, 57% (67%) at 10 hours, 53% (55%) at 12 hours and 39% (43%) at 14 hours. Conclusions This audit has shown that current practice results in a high proportion of vancomycin maintenance doses being administered at impractical times. Allowing a more flexible time window of 6-12 hours after the loading dose for administration of the first vancomycin maintenance dose could help to alleviate this problem and reduce the risk of early subtherapeutic vancomycin trough concentrations.