Gentamicin (Neonatal Formulary)

Audience

Age	Dose	Frequency	Comments
Less than 7 days after birth	5mg/kg	36 hourly	Initial starting dose. Adjust according to Therapeutic Drug Monitoring (see below).
IF less than 7 days after birth AND more than 32 weeks gestation, appears very unwell or blood culture grows Gram negative bacteria	5mg/kg	24 hourly Except in renal impairment.
7 days or more after birth	5mg/kg	24 hourly

Give by slow IV injection over 3 to 5 minutes.
Ensure adequate flushing if patient is also prescribed a penicillin or cephalosporin, due to incompatibilities.

see BNFC for full information
Nephrotoxicity
Prescribers should assess prior to prescribing and monitor whilst on treatment.
And check child is passing urine.
Nephrotoxicity may be compounded by other agents, eg, amphotericin, cephalosporins, ciclosporin, ibuprofen, indometacin, tacrolimus, vancomycin.
Auditory and vestibular function
Prescribers should monitor for signs of ototoxicity eg hearing loss, and refer to audiology if it develops, or if gentamicin is continued for more than 7 days.
Stop gentamicin if ototoxicity occurs, and refer to microbiology or an infection specialist for advice on future therapy.
Ototoxicity may be compounded by, eg, furosemide, indometacin and vancomycin; monitor renal function & fluid balance closely.
Venous irritation
This medicine has a low pH and may cause venous irritation and tissue damage in cases of extravasation.
If a central venous access device is unavailable, administer via a large peripheral vein.
Re-site cannula at first signs of inflammation.

(Jan 2021): Aminoglycosides: increased risk of deafness in patients with mitochondrial mutations
(Nov 2017): Potential for histamine-related adverse drug reactions with some batches

If a second dose of gentamicin is required: measure the trough level IMMEDIATELY BEFORE the second dose

NO concerns about renal function	Renal impairment OR any concern about renal function
Give the second dose WITHOUT waiting for the trough result.	WAIT for the trough result before giving the second dose OR discuss antibiotic choice with the consultant.

Action to take based on trough levels at 2nd dose
Less than 1mg/L	More than 1mg/L and less than 2mg/L		2mg/L or more
	36 hourly dosing	24 hourly dosing
No further routine monitoring required	ONLY 5 days of treatment planned: No further routine monitoring required. MORE THAN 5 days of treatment planned OR length of treatment course unknown: Take a trough level before 4th dose.	Take a trough level before 4th dose	Delay the next dose by 12 hours and re-check trough level. If less than 2mg/L, continue but extend the dosing interval by 12 hours for subsequent doses, ie, 36 to 48 hourly. Take a trough level before 4th dose.

Repeat CRP 18 to 24 hours after starting antibiotics and first sample for CRP.
If CRP remains low (less than 10) and baby is clinically well, discontinue the gentamicin.
If blood cultures remain negative but CRP has risen above 10, duration of antibiotics will be 5 to 7 days. Exact duration depends on if baby has been unwell and on return of CRP towards normal values

See: Prevention and management of neonatal sepsis guideline for further detail.

Action to take based on trough levels at 4th (or any subsequent) dose
Less than 1mg/L	1mg/mL or more
No further routine monitoring required	Delay the next dose by 12 hours and re-check trough level. If less than 1mg/mL extend the dosing interval by 12 hours for subsequent doses, ie, 36 hourly to 48 hourly, 24 hourly to 36 hourly.
Follow this advice for subsequent doses after result of trough level at 4th dose available.

A peak level may be measured if required. See BNFc.

Extended interval gentamicin – neonatal parenteral drug monograph, AMH Neonatal Unit, Department of Pharmacy, NHS Grampian.
Injectable Medicines Guide paediatric monograph for Gentamicin accessed 10.4.23
BNF for Children accessed 10.4.23
National Patient Safety Agency. Safer use of intravenous gentamicin for neonates. (Gentamicin Alert.) (Version 1, 03 Feb 2010) Available at: http://www.nrls.npsa.nhs.uk/ resources/type/alerts/?entryid45=66271&q=0%c2 %acgentamicin%c2%ac [Accessed 10 Apr 2023]