Amikacin (Antimicrobial)

A once daily regimen is preferred as this is safer for patients and more efficient without being any less effective than a multiple daily dose regimen.  For dosing in non-tuberculous mycobacterial infections (NTM), seek advice from Pharmacy as a different dosing schedule is used.

Usual dose is 15mg/kg (maximum 1.5g) once a day with a maximum of 15g per course.  There is a higher risk of ototoxicity with higher cumulative doses and longer treatment courses.  The dose should be adjusted according to weight and degree of renal impairment.  Glucose 5% is the preferred diluent to reduce sodium load.

DO NOT use eGFR.  Calculate the creatinine clearance (CrCl) using the following equation (Cockcroft Gault)

Calculate the amikacin dose using the dosing table below.  Use actual body weight unless body mass index (BMI) is greater than 30 kg/m² where adjusted body weight (AdjBW) is recommended:

Adjusted body weight = IBW + (0.4 x (actual body weight – IBW))

Ideal bodyweight (IBW):

• Male = 50kg + 2.3kg per inch over 5ft OR 50kg + 2.3kg per 2.5cm over 152cm
• Female = 45kg +2.3kg per inch over 5ft OR 45kg + 2.3kg per 2.5cm over 152cm

If creatinine is not known, give 7.5mg/kg (maximum 600mg, diluted in 100ml glucose 5% and given over 30 minutes) and seek advice from Pharmacy.

As the monitoring of amikacin levels is out-sourced to a laboratory outside NHS Highland, use in patients with CrCl below 20ml/min is not advised. Seek advice from Microbiology or Pharmacy on alternative options.

Prior to the second dose, take a trough level (immediately prior to dose) then a peak level (1 hour post dose) and then repeat these levels every 2 to 3 days thereafter.  Once levels are in the target range and renal function is stable, the frequency of testing can be reduced.

Doses should continue to be administered whilst awaiting level as long as renal function is stable.

Samples are sent via Raigmore Hospital Microbiology Laboratory to Bristol for analysis and are only processed Monday to Friday.  Results should be available the following day but if sent on a Friday the result would be back Monday at the earliest and later if this is a bank holiday.

Careful consideration of the limited availability of monitoring is required before starting therapy on a Thursday or Friday as levels will not be available at the correct time to inform dosing.  Microbiology should be involved and discussions had about the safety of treatment and whether or not an alternative therapy could be used in these situations.

Seek advice from Pharmacy for dose adjustment if levels are out with the target range.

Amikacin can cause nephrotoxicity and ototoxicity (cochlear and vestibular).  The risk of amikacin toxicity increases with increasing duration of therapy and may occur irrespective of amikacin concentration.

Nephrotoxicity:

• Signs of amikacin nephrotoxicity include; reduced urine output/ oliguria or increased creatinine.
• Consider an alternative antimicrobial agent if creatinine is increasing or the patient becomes oliguric.

Oto/vestibular toxicity:

• Signs of amikacin oto/vestibular toxicity include: new tinnitus, dizziness, poor balance, hearing loss, oscillating vision.
• Patients should be advised to report signs of ototoxicity and they should be asked about any signs and symptoms of ototoxicity regularly.  This discussion should be documented in the patient’s clinical notes.  If ototoxicity is suspected, stop amikacin therapy immediately and discuss with an infection specialist.
• If amikacin continues for more than 7 days, suggest referral to audiology for assessment.  Consider baseline audiometry prior to courses anticipated to be longer than 7 days from the outset.

• NHS Greater Glasgow and Clyde Adult Therapeutics Handbook Amikacin Dosing Guidance.  Updated 19^th October 2023.  Accessed 12/2/25 via https://rightdecisions.scot.nhs.uk/media/rl0e5l0x/amikacin-dosing-guidelines-in-adults-1099.pdf