Background:The clinical microbiology team observed that patients were not receiving all prescribed doses of vancomycin. Ward staff was confused about ordering and interpreting vancomycin therapeutic drug monitoring (TDM) levels. Aim: To audit the incidence of vancomycin dose omission. To implement a series of interventions to improve vancomycin dose administration, and to repeat the audit process to assess these interventions. Methods: Three prospective audits were conducted to assess the impact of vancomycin TDM on administration of vancomycin. After the first audit, a number of changes in the TDM process were undertaken. After review of the second audit, a senior pharmacist coordinated ward-based pharmacists in assisting staff to interpret levels, and TDM interpretative charts were designed for drug charts. Following the third audit, feedback to hospital management and a plan for ongoing education were undertaken. Results: There was a significant reduction in the number of vancomycin doses held inappropriately in the third (10% (78/782) of prescribed doses) when compared to the first audit (16% (161/1007) of doses) (p,0.01). Of doses that were held inappropriately, there was a significant decrease in doses held for no apparent reason in audit 3 (16% (27/170) of prescribed doses) when compared to audit 1 (25% (69/282) of doses) (p,0.05). Conclusions:The interventions resulted in a 37.5% reduction in inappropriately held vancomycin doses over a one-year period; 10% of doses are still being held inappropriately. This study highlights the difficulties in identifying barriers to change and changing healthcare worker behaviour.

SummaryA clinical case series is presented to characterize the interaction between carbapenem antibiotics and sodium valproate. Six illustrative cases are presented in which carbapenem therapy led to the rapid depletion of serum valproate levels, and one case is presented to demonstrate the difficulty of initiating valproate therapy in patients already on meropenem. The speed of valproate depletion after the initiation of carbapenem therapy, the effect of treatment duration, clinical manifestations, delay in valproate level normalization after carbapenem therapy, the efficacy of supplemental valproate doses, and the usefulness of valproate dose escalation are evaluated. Five out of the 7 patients became acutely symptomatic owing to their subtherapeutic valproate levels. The presented cases also highlight the relatively slow normalization of valproate levels after discontinuation of the antibiotic therapy. Our cases suggest that the interaction is not absorption‐mediated because all of our patients received intravenous valproate. We observed that the introduction of alternative antiepileptic drugs (AEDs) may be preferable to valproate dose escalation, which is ineffective in the presence of concomitant meropenem therapy. The characterization and recognition of this interaction have implications for the management of a particularly vulnerable patient cohort.

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