What is the recommended dose for amikacin (antibiotic)?

Amikacin Dosing Recommendations

The standard dose of amikacin for adults with normal renal function is 15 mg/kg/day, administered either as a single daily dose or divided into 7.5 mg/kg every 12 hours or 5 mg/kg every 8 hours, with a maximum daily dose not exceeding 1.5 grams. 1, 2, 3

Standard Dosing by Administration Schedule

Once-Daily Dosing (Preferred)

• 15 mg/kg as a single daily dose is the recommended regimen for most adult patients with normal renal function 1, 2, 3
• This achieves peak concentrations of 40-45 mg/L and trough concentrations of 1-2 mg/L 4
• Once-daily dosing demonstrates superior clinical cure rates (83% vs 66%) and bacteriological cure rates (81% vs 58%) compared to twice-daily dosing 5
• Once-daily dosing also results in less nephrotoxicity (21% vs 35% creatinine elevation) compared to twice-daily regimens 5

Divided Dosing (Alternative)

• 7.5 mg/kg every 12 hours OR 5 mg/kg every 8 hours 2, 3
• This achieves lower peak concentrations (approximately 24-28 mg/L) but higher trough levels (3-5 mg/L) 4

Age-Based Dose Adjustments

Patients Over 59 Years

• Reduce dose to 10 mg/kg/day (maximum 750 mg) due to increased risk of ototoxicity with age 1, 2
• For a 50 kg patient over 59 years, this translates to 500 mg daily 1

Newborns and Infants

• Loading dose: 10 mg/kg initially 3
• Maintenance: 7.5 mg/kg every 12 hours 3

Children and Adolescents

• 20 mg/kg/day for critically ill patients under 1 year of age 5
• 15 mg/kg/day for patients over 1 year of age 5

Renal Impairment Dosing

Principle

• Maintain the mg/kg dose at 12-15 mg/kg but reduce frequency to preserve concentration-dependent bactericidal effect 1, 2, 6

Specific Adjustments

• Mild-moderate impairment: Administer every 2-3 days at 12-15 mg/kg 2
• ESRD patients: Two to three times per week at 12-15 mg/kg 6
• Always administer after dialysis to prevent premature drug removal and ensure directly observed therapy 6

Calculation Method (When Creatinine Clearance Unknown)

• Dosing interval (hours) = serum creatinine (mg/dL) × 9 3
• Example: If serum creatinine is 2 mg/dL, administer 7.5 mg/kg every 18 hours 3

Obese Patients

• Calculate dose using: ideal body weight + 40% of excess weight 2

Therapeutic Drug Monitoring Targets

Peak Concentrations

• Daily dosing: 25-35 mg/L 2
• Three times weekly dosing: 65-80 mg/L 2
• Measure 30-90 minutes after injection 3
• Avoid peaks above 35 mg/L 3

Trough Concentrations

• Target: <5 mg/L 2
• Avoid troughs above 10 mg/L 3
• Measure just prior to next dose 3

Monitoring Schedule

• Measure peak levels within the first week of therapy 2
• Measure trough levels weekly for 4 weeks, then every 2 weeks when stable 2
• Baseline: audiogram, vestibular testing, Romberg testing, serum creatinine 1
• Monthly: renal function assessment and questioning about auditory/vestibular symptoms 1

Duration of Therapy

• Usual duration: 7-10 days 3
• Initial frequency: 5-7 days per week 1
• After 2-4 months or culture conversion (tuberculosis): reduce to 2-3 times weekly 1
• If treatment extends beyond 10 days, re-evaluate necessity and intensify monitoring of serum levels, renal, auditory, and vestibular functions 3

Critical Warnings

Contraindications

• Pregnancy: absolute contraindication due to risk of fetal nephrotoxicity and congenital hearing loss 2

Common Pitfalls to Avoid

• Do not administer before dialysis in ESRD patients—this causes premature drug removal and treatment failure 6
• Do not exceed 1.5 grams total daily dose regardless of weight 1, 3
• Ototoxicity risk increases dramatically with cumulative doses above 100-120 grams 1
• Avoid concurrent loop diuretics, which significantly increase ototoxicity risk 1, 6

Special Consideration for CNS Infections

• Amikacin has poor CSF penetration even with meningitis, which may necessitate higher systemic doses for tubercular meningitis 1