Amikacin
Amikacin is a potent aminoglycoside antibiotic primarily active against severe Gram-negative bacterial infections, *Staphylococcus aureus*, and *Nocardia* spp. It is particularly valuable for treating infections resistant to other aminoglycosides like gentamicin. **Clinical Pearl:** Streptococci and anaerobic bacteria are typically resistant. Activity is significantly reduced in low-oxygen environments (e.g., abscesses, necrotic tissue). > **Warning:** Amikacin has poor penetration across biological membranes; systemic levels require parenteral administration, and it achieves very limited concentrations in the CNS and ocular fluids. It carries significant risks of **nephrotoxicity** and **ototoxicity**.
Mechanism: Aminoglycosides irreversibly bind to the **30S ribosomal subunit** of susceptible bacteria, inhibiting bacterial protein synthesis. They exhibit **concentration-dependent killing** โ leading to a marked **post-antibiotic effect** (PAE). This allows for prolonged dosing intervals (e.g., q24h), which maximizes bacterial kill rates while minimizing accumulation in renal tubular cells, thereby reducing toxicity.
Dosing by species
- Susceptible bacterial infections ยท 15-30 mg/kg ยท IV/IM/SC ยท q24h ยท Not specified ยท IV doses should be given slowly over 30-60 minutes.
- Susceptible bacterial infections in Greyhounds and sight hounds ยท 12 mg/kg ยท IV/IM/SC ยท q24h ยท Not specified ยท Lower dose recommended due to a lower volume of distribution in these breeds.
- Sepsis ยท Higher than standard doses ยท IV/IM/SC ยท q24h ยท Not specified ยท Recommended by some authors, but carries an increased risk of adverse effects.
- Local infections (e.g., joints, bladder) ยท Varies ยท topical ยท Varies ยท Not specified ยท Considered if the site is easily accessible and if the animal shows signs of systemic nephrotoxicity.
- Susceptible bacterial infections ยท 10-15 mg/kg ยท IV/IM/SC ยท q24h ยท Not specified ยท IV doses should be given slowly over 30-60 minutes.
- Sepsis ยท Higher than standard doses ยท IV/IM/SC ยท q24h ยท Not specified ยท Recommended by some authors, but carries an increased risk of adverse effects.
- Local infections (e.g., joints, bladder) ยท Varies ยท topical ยท Varies ยท Not specified ยท Considered if the site is easily accessible and if the animal shows signs of systemic nephrotoxicity.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Animals with pre-existing reduced renal function (unless benefits outweigh risks)
- Dehydrated patients (without concurrent fluid therapy)
Adverse effects
- Nephrotoxicity (tubular necrosis)
- Ototoxicity (vestibular and auditory dysfunction)
- Neuromuscular blockade (rare but possible)
Drug interactions
- Beta-lactam antimicrobials (Penicillins, Cephalosporins) ยท In vivo synergism against susceptible bacteria; however, they can cause in vitro inactivation of amikacin. Do not mix in the same syringe. ยท moderate
- Amphotericin B ยท Increased risk of severe nephrotoxicity. ยท major
- Furosemide ยท Increased risk of ototoxicity and nephrotoxicity. ยท major
- Heparin ยท In vitro inactivation of amikacin. Do not mix in the same syringe. ยท moderate
- Neuromuscular blocking agents ยท Potentiation of neuromuscular blockade. ยท major
Monitoring
- Serum amikacin levels (peak for efficacy, trough for toxicity)
- Renal function (BUN, serum creatinine, urinalysis for casts/proteinuria)
- Hydration status
- Auditory and vestibular function (if possible)
Overdose
Overdosage significantly increases the risk of **acute tubular necrosis (nephrotoxicity)** and **vestibular/auditory damage (ototoxicity)**. Treatment is supportive. Discontinue the drug immediately and initiate aggressive intravenous fluid therapy to promote diuresis and maintain glomerular filtration rate.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.