What is the recommended adult dose of Amikacin (generic name) for intravenous (IV) or intramuscular (IM) administration?

Adult Dose of Amikacin

For adults with normal renal function, administer amikacin 15 mg/kg/day IV or IM, divided as either 7.5 mg/kg every 12 hours or 5 mg/kg every 8 hours, with a maximum total daily dose not exceeding 15 mg/kg/day. 1

Standard Dosing Regimens

Daily Dosing Options

• 15 mg/kg once daily is the preferred regimen for most infections, offering equivalent efficacy with reduced nephrotoxicity 2, 3
• 7.5 mg/kg every 12 hours (divided twice daily) is the traditional FDA-approved regimen 1
• 5 mg/kg every 8 hours (divided three times daily) is an alternative for conventional dosing 1

Intermittent High-Dose Regimen

• 15-25 mg/kg three times weekly is recommended when prolonged therapy is needed (e.g., non-tuberculous mycobacterial infections) to reduce cumulative toxicity 2, 3, 4

Age-Specific Adjustments

Older Adults (>59 years)

• Reduce dose to 10 mg/kg/day due to significantly increased risk of ototoxicity and nephrotoxicity 3, 5, 4
• This age-related dose reduction is critical and recommended by the Centers for Disease Control and Prevention 3

Obesity Dosing Adjustment

For markedly obese patients, calculate the adjusted dose using ideal body weight plus 40% of excess weight 2, 3, 5:

• Male ideal body weight (kg) = 50 + (2.3 × height in cm above 152.4)/2.54 2
• Female ideal body weight (kg) = 45.5 + (2.3 × height in cm above 152.4)/2.54 2

Renal Impairment Dosing

Critical principle: In renal impairment, maintain the milligram dose (12-15 mg/kg) but reduce the frequency to 2-3 times per week—never reduce the individual dose 3, 5, 4:

• Administer after dialysis in hemodialysis patients to facilitate directly observed therapy and avoid premature drug removal 3, 5
• Alternatively, extend the dosing interval by multiplying the patient's serum creatinine by 9 (e.g., if creatinine is 2 mg/dL, give the standard 7.5 mg/kg dose every 18 hours) 1

Administration Guidelines

Intravenous Administration

• Dilute in 100-200 mL of 0.9% sodium chloride or 5% dextrose 1
• Infuse over 30-60 minutes in adults 1
• Never physically premix with other drugs—administer separately 1

Intramuscular Administration

• Same dosing as IV route 1
• Adjust based on therapeutic drug monitoring 1

Therapeutic Drug Monitoring

Target Levels

• Trough: <5 mg/L to prevent toxicity 2, 3, 5, 4
• Peak (daily dosing): 25-35 mg/L 2, 3, 5, 4
• Peak (three times weekly dosing): 65-80 mg/L 2, 3, 4

Monitoring Schedule

• Measure peak serum level within the first week 2, 4
• Measure trough levels weekly for 4 weeks, then every 2 weeks when stable 2, 5, 4
• For peak measurement, draw sample 90-120 minutes after infusion ends and extrapolate back to time zero, or draw at 60 minutes (may underestimate true peak) 2

Safety Monitoring

Baseline Assessment

• Audiogram, vestibular testing, Romberg testing, and serum creatinine 3

Ongoing Monitoring

• Monthly renal function assessment (serum creatinine) 3, 4
• Question about auditory/vestibular symptoms monthly 3
• Repeat audiogram if any symptoms of eighth nerve toxicity develop 3

Toxicity Rates

• Nephrotoxicity occurs in 8.7% overall, but only 3.4% in patients without risk factors 3
• Ototoxicity (high-frequency hearing loss) occurs in 1.5-24% of patients, with higher rates in longer treatment courses 3

Duration of Therapy

• Usual duration: 7-10 days 1
• If treatment beyond 10 days is considered, reassess the need for amikacin and intensify monitoring of serum levels, renal function, and auditory/vestibular function 1
• Definite clinical response should occur within 3-5 days; if not, stop therapy and recheck antibiotic susceptibility 1

Critical Pitfalls to Avoid

• Never use fixed 500 mg doses regardless of weight—this ignores patient weight entirely and risks underdosing and treatment failure 4
• Never reduce the milligram dose in renal impairment—instead extend the dosing interval 3, 4
• Never continue beyond 10 days without reassessing drug levels and toxicity monitoring 3
• Absolutely contraindicated in pregnancy due to risk of fetal nephrotoxicity and congenital hearing loss 3, 5