36 Hour Gentamicin Calculator

This tool has been used to check safe prescription of gentamicin by medical staff on the general paediatrics and special care baby units. It is also used by nursing staff to ensure administration times are accurate and safe.

CDDFT is made up of 2 medium sized district general hospitals; each with a paediatric unit and a special care baby unit.  Many of our babies are commenced on intravenous antibiotics for potential infection, following the implementation of a NICE guideline.

We experienced some difficulties in the administration of intravenous gentamicin at 36 hour intervals ( as the NICE guideline recommends) – both prescription and administration errors, with some doses given too early and some too late.


Although this was seen in a minority of cases, we felt that making a dose interval calculator would allow staff to check the timing for prescription and administration and help reduce the number of errors.


This is a simple Excel based calculator that can be used to calculate the time intervals for gentamicin administration at 36 hour intervals in the neonatal setting.


This tool has been used to check safe prescription by medical staff and has also been used by nursing staff to ensure administration times are accurate and safe. It was introduced along with prescribing and administration workshops for medical and nursing staff respectively.

With the introduction of this calculator and the workshops we have found that dose interval administration errors have been practically eradicated (but we continue to monitor the situation).  The calculator does not always need to be used, but is available, online, for staff to access when prescribing and administering this medication.

This tool could be useful in all Trusts where the NICE guidance is used.

Challenges and Learning

Once I was able to find assistance with Excel this was straightforward to create and begin to use.

This tool has been approved within our Trust by Pharmacy and the Clinical Standards and Therapeutics Committee, and as such is easily accessible via the hospital intranet. Currently formulae within the spreadsheet run until the year 2020, and can be updated after this time.


Project Lead: Dr Mehdi Garbash, Consultant Paediatrician

Organisation: County Durham & Darlington NHS Foundation Trust

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