Amikacin

Amikacin is a parenteral aminoglycoside antibiotic most commonly used to treat gram-negative and staphylococcal infections. Its use should be reserved for severe infections proven or strongly suspected to be resistant to first line antibiotics.

Metabolism and pharmacodynamics

  • Half-life: 30 minutes to 2 hours
  • Elimination: Renal

Mechanism of action and spectrum of activity

  • Bactericidal; Concentration-dependent with significant post-antibiotic effect
  • Irreversible binding to the 30S ribosomal subunit on susceptible bacteria, inhibiting protein synthesis
  • Gram-negative aerobes and some gram-positive aerobes (Klebsiella, Proteus, Pseudomonas, Salmonella, Enterobacter, Serratia, Shigella, Mycoplasma, and Staphylococcus.

Advantage over other drugs in the same class (gentamicin)

  • Improved activity against some strains of Pseudomonas aeruginosa, Serratia and Proteus spp.

Precautions/contraindications

  • Half-life is significantly prolonged in animals with renal dysfunction
  • Correct hydration deficits and maintain hydration during treatment
  • Extreme caution with current or previous renal azotemia
  • Monitor closely for renal compromise in patients treated concurrently with furosemide and NSAIDs
  • Hypersensitivity to amikacin is the only absolute contraindication

Adverse Effects

  • Renal toxicity (tubular necrosis) – more common with prolonged therapy and/or short dosing intervals (q12 hours)
    • Diagnosed by presence of proteinuria, urinary casts, azotemia, isosthenuria/hyposthenuria, nonoliguric renal failure
    • Reversible once drug is discontinued
  • Ototoxicity – 8th cranial nerve toxicity – can be auditory or vestibular dysfunction
  • Neuromuscular blockage
  • Facial edema
  • Peripheral neuropathy
  • Injection site pain
  • Nausea/vomiting

Dosing recommendations

  • For treatment of documented infections sensitive to amikacin
    • Dogs: 15-30 mg/kg IV, IM or SQ q24 hours
    • Cats: 15-20 mg/kg IV, IM or SQ q24 hours
  • Dose should be reduced for sighthounds (due to lower volume of distribution) and obese patients
  • In patients with renal azotemia, use with extreme caution and only if no other antibiotic options exist

Dosage forms

  • 250 mg/ml (2ml vials currently stocked at Ethos East hospitals)
  • 50mg/ml

Preparation and administration

  • Dilute to 5 mg/ml with 0.9% NaCl, LRS, or 5% dextrose in water (D5W) – exact instructions will depend on concentration and size of vial in hospital (see below for an example)
  • Diluted solutions are stable at room temperature for 24 hours and up to 60 days in the fridge
  • If administering IV, give dilute solution over 30 minutes.

Recommended patient monitoring

  1. Baseline: kidney values and urinalysis
  2. Every other day during treatment: urine sediment evaluation
  3. If treating longer than 7 days: kidney values q5-7 days
  4. As needed: kidney values if signs of nausea, dehydration, change in urine production. Reduce or discontinue dosing if azotemia or tubular casts develop.

Example

A 10kg dog has a resistant wound infection that is sensitive to amikacin. The dog is stable and ready to be discharged from the hospital. The owner will come to the hospital daily for treatment.

  1. Add the 2ml vial of amikacin (250mg/ml) to 100ml NaCl to make a 5mg/ml solution
    1. If multiple doses can be given from the same vial, store the diluted solution in the fridge. Only enter an amikacin vial charge when a new vial is opened. Otherwise, charge a miscellaneous injection fee.
  2. This dog’s dose is 15 mg/kg = 150mg
  3. The instructions should read: Give 150mg (30ml) of the 5mg/ml Amikacin dilution under the skin q24.
    1. Some clinicians may opt to treat concurrently with a separate dose of SQ fluids.
  4. Label the diluted solution clearly with the patient’s name, date of dilution, drug name, and concentration. Note location of diluted solution in the patient medical record.

References

  • Plumb’s Veterinary Drugs online. Amikacin monograph. Accessed March 14, 2018.
  • Global RPh. Amikacin monograph. Accessed March 14, 2018.

Additional resources

Last updated: 2018-03-30