What is the recommended dosing for amikacin (antibiotic)?

Amikacin Dosing Recommendations

The recommended standard dosing for amikacin in adults with normal renal function is 15 mg/kg/day administered as a single daily dose (maximum 1.0 g/day), with dose reduction to 10 mg/kg/day (maximum 750 mg) for patients over 59 years of age. 1, 2, 3

Adult Dosing

Normal Renal Function

• Standard dosing: 15 mg/kg/day IV or IM as a single daily dose 1, 2, 3
  • Maximum: 1.0 g/day
  • Duration: Usually 7-10 days (limit to short term whenever feasible) 3
• Alternative regimens:
  • 15 mg/kg/day divided into 2 doses (7.5 mg/kg q12h) 3
  • 15 mg/kg/day divided into 3 doses (5 mg/kg q8h) 3
• For patients >59 years: Reduce to 10 mg/kg/day (maximum 750 mg) 1
• For uncomplicated UTIs: 250 mg twice daily may be used 3

Impaired Renal Function

Two approaches can be used 3:

1. Normal dose at prolonged intervals:

   • Calculate interval (hours) = patient's serum creatinine × 9
   • Example: If serum creatinine is 2 mg/dL, give 7.5 mg/kg every 18 hours

2. Reduced dose at fixed intervals:

   • Dosing frequency should be reduced to 2-3 times weekly
   • Maintain dose at 12-15 mg/kg per dose to preserve concentration-dependent bactericidal effect 1

Pediatric Dosing

• Children: 15-22.5 mg/kg/day IV 2
• Neonates: Dosing based on gestational age and postnatal age 1:
  • Gestational age <30 weeks:
    • Postnatal age <14 days: 15 mg/kg IV q48h
    • Postnatal age >14 days: 15 mg/kg IV q24h
  • Gestational age 30-34 weeks:
    • Postnatal age <14 days: 15 mg/kg IV q36h
    • Postnatal age >14 days: 15 mg/kg IV q24h
  • Gestational age >34 weeks:
    • Postnatal age ≤7 days: 15 mg/kg IV q24h
    • Postnatal age >7 days: 18 mg/kg IV q24h

Therapeutic Drug Monitoring

Monitoring serum concentrations is essential to ensure efficacy and minimize toxicity 1, 2, 3:

• Target levels:
  • Peak (30-90 minutes after injection): 25-35 μg/mL
  • Trough (just before next dose): <5-10 μg/mL
• Avoid levels:
  • Peak >35 μg/mL
  • Trough >10 μg/mL

Monitoring Recommendations

• Baseline assessment:

  • Audiogram and vestibular testing
  • Romberg testing
  • Serum creatinine measurement 1

• During treatment:

  • Renal function: Monthly 1, 2
  • Auditory/vestibular symptoms: Monthly questioning 1
  • Repeat audiogram if symptoms of eighth nerve toxicity develop 1

Important Considerations

Efficacy

• Once-daily dosing has shown equal or better efficacy compared to multiple daily dosing regimens, with clinical cure rates of 83-90% 4, 5, 6
• Amikacin is effective in 88% of infections due to gentamicin-resistant pathogens 7

Toxicity Concerns

• Ototoxicity: Can cause deafness and vestibular dysfunction (less than streptomycin) 1
• Nephrotoxicity: May be more nephrotoxic than streptomycin 1
• Risk factors for toxicity:
  • Prolonged treatment
  • Higher total doses
  • Concurrent use of diuretics
  • Pre-existing renal impairment
  • Advanced age 1, 2

Contraindications

• Pregnancy (risk of fetal nephrotoxicity and congenital hearing loss) 1

Administration

• Can be given intramuscularly or intravenously 1, 3
• For IV administration, infuse over 30 minutes 4
• For patients on dialysis, administer after dialysis to facilitate directly observed therapy and avoid premature drug removal 1

Once-daily dosing has gained favor due to the concentration-dependent bactericidal effect of aminoglycosides and potentially reduced toxicity compared to multiple daily dosing 4, 5, 6. However, careful monitoring of drug levels and renal function remains essential regardless of dosing schedule.