What is the recommended dosage of intramuscular (IM) amikacin (Amikin)?

Amikacin Dosage Recommendations

For intramuscular amikacin in adults, administer 15 mg/kg/day as a single daily dose (maximum 1 g/day), reducing to 10 mg/kg/day (750 mg) for patients over 59 years of age. 1, 2

Standard Adult Dosing

• The recommended dose is 15 mg/kg/day administered intramuscularly or intravenously as a single daily dose, typically given 5-7 days per week initially 3, 1
• The maximum daily dose should not exceed 1 gram 3
• For patients over 59 years old, reduce the dose to 10 mg/kg/day (750 mg maximum) to account for age-related decline in renal function 3, 1, 2
• Once-daily dosing takes advantage of amikacin's concentration-dependent bactericidal activity and may reduce nephrotoxicity compared to divided dosing 4, 5

Pediatric Dosing

• Children should receive 15-30 mg/kg/day intramuscularly or intravenously as a single daily dose, with a maximum of 1 g/day 3
• In critically ill pediatric patients under one year of age, 20 mg/kg/day may be used with a loading dose of 25 mg/kg 5

Dosing in Renal Impairment

The dosing frequency must be reduced in renal insufficiency, but the milligram dose per administration should be maintained at 12-15 mg/kg to preserve bactericidal efficacy. 3, 1

• Reduce dosing frequency to 2-3 times weekly rather than reducing the individual dose, as smaller doses may compromise treatment efficacy 3, 2
• For hemodialysis patients, administer the drug after dialysis to facilitate directly observed therapy and prevent premature drug removal 3, 1
• In stage 3A CKD (GFR 40-59 mL/min), consider 7.5 mg/kg/day 6
• In stage 3B CKD (GFR 30-39 mL/min), reduce to 4 mg/kg/day 6
• In stage 4 CKD (GFR 15-29 mL/min), use either 4 mg/kg/day or 6 mg/kg every two days, though daily dosing appears more effective 6
• In stage 5 CKD on hemodialysis, use 5 mg/kg every two days after dialysis 6

Long-Term or Intermittent Therapy

• After the first 2-4 months or after culture conversion (particularly for tuberculosis or mycobacterial infections), reduce frequency to 2-3 times weekly while maintaining the 12-15 mg/kg dose per administration 3
• For intermittent dosing when prolonged therapy is needed, use 15-25 mg/kg per dose three times weekly to reduce cumulative toxicity 2

Critical Monitoring Requirements

Target trough levels <5 mg/L to prevent toxicity and peak levels of 25-35 mg/L for daily dosing or 65-80 mg/L for three-times-weekly dosing. 1, 2

• Measure peak serum levels within the first week of therapy 1, 2
• Monitor trough levels weekly for 4 weeks, then every 2 weeks when stable 1, 2
• Perform baseline audiogram, vestibular testing, Romberg testing, and serum creatinine measurement before initiating therapy 3
• Assess renal function monthly and question patients about auditory or vestibular symptoms 3, 2
• Repeat audiogram and vestibular testing if symptoms of eighth nerve toxicity develop 3

Important Safety Considerations

• Amikacin is absolutely contraindicated in pregnancy due to risk of fetal nephrotoxicity and congenital hearing loss 3, 1
• Ototoxicity occurs in approximately 1.5-24% of patients, with higher rates in those receiving longer treatment, higher doses, or concurrent diuretics 3
• Nephrotoxicity occurs in 8.7% of patients overall, but only 3.4% in those without risk factors 3
• Avoid fixed 500 mg doses regardless of patient weight, as this ignores body weight entirely and risks underdosing with treatment failure 2
• Use caution with concurrent nephrotoxic agents or in patients with baseline renal impairment 3, 2