What is the recommended dose of Amikacin (generic name) for patients with normal and impaired renal function?

Amikacin Dosing Guidelines

For patients with normal renal function, amikacin should be administered at 15 mg/kg/day (maximum 1.0 g/day) as a single daily dose, with dose reduction to 10 mg/kg/day (maximum 750 mg) for patients over 59 years of age. 1, 2

Standard Dosing for Normal Renal Function

Adults

• Normal dose: 15 mg/kg/day (maximum 1.0 g/day) as a single daily dose 1, 2
• Age > 59 years: Reduce to 10 mg/kg/day (maximum 750 mg) 1
• Administration: Intramuscular or intravenous, with IV infusion given over 30-60 minutes 2

Children

• Standard dose: 15-30 mg/kg/day (maximum 1.0 g/day) as a single daily dose 1, 2

Dosing in Renal Impairment

Amikacin requires significant dose adjustment in renal impairment due to its primarily renal clearance and increased risk of toxicity. Two approaches are recommended:

Method 1: Normal Dose at Extended Intervals

• Maintain the dose at 12-15 mg/kg but extend the interval between doses to 2-3 times per week 1, 2
• If creatinine clearance is unavailable, multiply serum creatinine by 9 to determine dosing interval in hours 3

Method 2: Reduced Dose at Fixed Intervals

• Give a loading dose of 7.5 mg/kg 3
• Calculate maintenance dose using the formula:

  Maintenance dose = (Observed CrCl / Normal CrCl) × Loading dose

• Administer every 12 hours 3

Hemodialysis Patients

• Administer amikacin after dialysis sessions to prevent premature drug removal 1, 2
• Maintain dose at 12-15 mg/kg to preserve concentration-dependent bactericidal effect 1

Therapeutic Drug Monitoring

Monitoring is essential to minimize toxicity while ensuring efficacy:

• Target peak levels: 25-35 μg/mL 2
• Target trough levels: <5-10 μg/mL 2
• Monitoring schedule:
  • Renal function: Monthly 1, 2
  • Auditory/vestibular function: Baseline and monthly 1, 2
  • Serum drug levels: Regularly, especially in renal impairment 2

Important Considerations and Cautions

Toxicity Risks

• Ototoxicity: Can cause hearing loss in 1.5-24% of patients, with higher risk at longer treatment durations and higher doses 1
• Nephrotoxicity: Occurs in 3.4-8.7% of patients, with higher risk in those with baseline renal impairment, larger cumulative doses, or concurrent nephrotoxic agents 1

Contraindications

• Pregnancy: Contraindicated due to risk of fetal nephrotoxicity and congenital hearing loss 1, 2
• Drug interactions: Avoid concurrent use with other aminoglycosides and use caution with loop diuretics due to increased ototoxicity risk 2

Duration of Treatment

• Standard duration is typically 7-10 days 3
• For tuberculosis treatment, initially daily dosing (5-7 days/week), then reducing to 2-3 times weekly after 2-4 months or after culture conversion 1

Clinical Pearls

• Single daily dosing provides higher peak concentrations that enhance bactericidal effect while allowing longer drug-free periods to reduce toxicity 2
• The FDA label recommends 15 mg/kg/day divided into 2-3 doses for traditional dosing, but more recent guidelines support once-daily dosing 3, 1
• Research shows once-daily dosing is as effective as twice-daily dosing with potentially less nephrotoxicity 4, 5
• Smaller doses may reduce efficacy due to concentration-dependent killing 1

By following these guidelines and carefully monitoring patients, amikacin can be used effectively while minimizing the risk of serious adverse effects.