Gentamicin, an aminoglycoside antibiotic, requires therapeutic drug monitoring to decrease the risk of nephrotoxicity and ototoxicity. We audited compliance with our dosing and monitoring guidelines since adoption of the Barnes-Jewish Nomogram for once daily 5mg/kg dosing in September 2018.


We retrospectively reviewed 62 patients who received 171 gentamicin doses with 173 accompanying levels taken between 1/11/18 and 31/1/19.


The audit demonstrated overall poor adherence to guidelines. Only 50% of patients received the correctly calculated dose. 40% of gentamicin levels were taken between 6-14 hours resulting in a large number of uninterpretable levels requiring additional actions e.g. repeat levels. 50% of follow up doses were given in the correct time frame. For patients with normal renal function twice weekly monitoring is recommended. In all cases (n=35) where this applied levels were monitored more frequently that indicated. U&Es were regularly monitored for all patients and we did not identify any acute kidney injury.


The Barnes-Jewish nomogram was adopted to provide a standardised evidence based monitoring system for gentamicin. However our audit demonstrates the guidance was not well executed clinically. There appeared to be a lack of appreciation and responsibility for monitoring and interpretation of levels. This resulted in erratic sampling, unnecessary levels, and delayed doses. As a result of this audit we intend to adopt a simpler trough level system based on the gentamicin SPC. Our audit demonstrates the need to evaluate service improvement implementations since theoretical benefits do not always translate in to clinical practice

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License.

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