Amikacin

Nephrotoxicity:

• Dose-dependent
• Ensure good hydration
• Avoid co-prescription of nephrotoxins (e.g. furosemide)

Vestibular/ototoxicity:

• Dose-indepedent
• Can occur within 72 hours (though more commonly after 10 days)
• Symptoms: dizzy, ataxia, nausea, vomiting, bobbing oscillopsia (vertical bouncing of surroundings), hearing loss.

If therapy continues for >7d, obtain baseline audiometry then repeat monthly.

If ototoxicity/vestibulotoxicity is suspected, discontinue aminoglycoside therapy, refer to ENT for assessment and call microbiology to discuss alternative antimicrobials.

Where possible, double check your calculations with the ward pharmacist before prescribing.

1. Calculate the patient's creatinine clearance

• Calculate using patient's age, height, weight & serum creatinine.
• Calculator available here (NB: Intranet only)
• Other online calculators can be used as long as they use the Cockcroft-Gault formula
• As a last resort calculate manually. 

2. Decide on using Maximum or Actual body weight

• Compare the patient's actual weight against the maximum body weight for the patient's height on this table here. 
• For the next step use whichever weight is lower of the actual or maximum weight.

3. Prescribe Amikacin dose

Using the table below, based on the calculated creatinine clearance, to choose the mg/kg dose that applies to your patient.

• Round the dose up to the nearest 50mg.
• Maximum dose is 1500mg daily.

Prescribe the calculated amikacin dose once daily on the patient's drug chart or on HEPMA (use the XH24, 24 hourly dosing)

• Choose a sensible time that will facilitate pre and post dose levels to be monitored.
• Refer to NHS Lothian IV Guide for details of administration.

4. Document on TRAK the calculation

Use TRAK backslash code \amikacin to document outcome.

AMIKACIN DOSING CALCULATIONS

Height (cm):

Weight (kg):

Creatinine (mmol/l):

MAXIMUM or ACTUAL body weight used in calculations (whichever is lower): 

Dosage:

Day of first trough/peak level:

SIGNED:

Checked with pharmacist (Y/N):

• Check U+Es daily; if renal function changes significantly, re-calculate creatinine clearance and adjust dose.
• Drug monitoring is performed at the WGH only, see here
• Start monitoring trough & peak levels with the second dose, then every 2 days until targets have been achieved consistently. Then discuss monitoring interval with clinical pharmacist.
• Outpatients with stable levels require trough monitoring only.
• Document peak/trough levels on TRAK, along with dose adjustments made if applicable  (see below).

Target levels (mg/l)

Discuss dose adjustment with clinical pharmacist.

• J Antimicrob Chemother (2016) 71 (10): 2754-2759.
• UKMI Medicines Q&As: How should antibiotics be dosed in obesity?