What is the appropriate dosing for intramuscular (IM) administration of amikacin?

From the Guidelines

Amikacin should be dosed at 15 mg/kg per day intramuscularly, with a maximum daily dose of 1.0 g/day, usually given as a single daily dose, 5-7 days a week, for adults with normal renal function, as recommended by the American Thoracic Society 1. When administering amikacin IM, it is essential to inject deeply into a large muscle mass, such as the gluteal muscle or lateral thigh, and rotate injection sites to minimize local irritation.

• The dosing frequency should be reduced for persons with renal insufficiency, to 12–15 mg/kg two or three times per week 1.
• For adults greater than 59 years of age, the dose should be reduced to 10 mg/kg per day (750 mg) 1.
• Children should receive a maximum dose of 15–30 mg/kg per day (1 g/day) as a single daily dose 1. Therapeutic drug monitoring is crucial when using amikacin, with peak levels drawn 30-60 minutes after injection and trough levels just before the next dose, to minimize the risk of toxicity and ensure effective treatment.
• Peak levels should be targeted at 20-30 mcg/mL, and trough levels should be targeted at <8 mcg/mL. The duration of therapy typically ranges from 7-10 days, depending on the infection being treated, and amikacin is effective against many gram-negative bacteria, including Pseudomonas aeruginosa and some drug-resistant organisms.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION The patient's pretreatment body weight should be obtained for calculation of correct dosage. ... Intramuscular Administration for Patients with Normal Renal Function The recommended dosage for adults, children and older infants (see WARNINGS box) with normal renal function is 15 mg/kg/day divided into 2 or 3 equal doses administered at equally-divided intervals, i.e., 7.5 mg/kg q12h or 5 mg/kg q8h.

DOSAGE GUIDELINES ADULTS AND CHILDREN WITH NORMAL RENAL FUNCTION Patient WeightDosage lbskg7.5 mg/kg5 mg/kg q12hORq8h 99 45 337.5 mg 225 mg 110 50 375 mg 250 mg 121 55 412.5 mg 275 mg 132 60 450 mg 300 mg 143 65 487.5 mg 325 mg 154 70 525 mg 350 mg 165 75 562. 5 mg 375 mg 176 80 600 mg 400 mg 187 85 637.5 mg 425 mg 198 90 675 mg 450 mg 209 95 712. 5 mg 475 mg 220 100 750 mg 500 mg

The recommended dosage of amikacin for intramuscular (IM) administration in patients with normal renal function is:

• 15 mg/kg/day divided into 2 or 3 equal doses
• Alternatively, 7.5 mg/kg every 12 hours or 5 mg/kg every 8 hours. The dosage may vary based on the patient's weight, as outlined in the dosage guidelines table. 2

From the Research

Amikacin Dosing

To dose amikacin intramuscularly (IM), several factors must be considered, including the patient's renal function.

• The initial dose of amikacin can be 7.5 mg/kg, as used in a study published in 3.
• However, this dose may need to be adjusted based on the patient's renal function, as amikacin is primarily excreted by the kidneys.
• A study published in 4 found that the half-life of amikacin is related to the level of serum creatinine, and that the half-life can be predicted using a nomogram or by measuring the rate of creatinine clearance.
• Another study published in 5 developed a population-based pharmacokinetic (PBPK) model to predict amikacin plasma concentrations in critically ill oncologic patients, and found that dose stratification based on renal function can help achieve optimal drug concentrations.
• The study in 5 suggested the following dosing regimens for patients with normal renal function (creatinine clearance ≥ 60 mL/min): 20 mg/kg every 24 hours, 25 mg/kg every 24 hours, 25 mg/kg every 48 hours, or 30 mg/kg every 72 hours.
• For patients with impaired renal function (creatinine clearance < 60 mL/min), the study in 5 suggested the following dosing regimens: 7.5 mg/kg every 24 hours, 15 mg/kg every 24 hours, 15 mg/kg every 48 hours, or 20 mg/kg every 36 hours.
• A study published in 6 evaluated the predictive performance of several renal function equations to describe amikacin elimination, and found that the revised Lund-Malmö (rLM) and CKD-EPI equations showed superior predictive performance.
• The study in 7 found that the rate of plasma clearance, half-life, and volume of distribution of amikacin are related to the rate of clearance of serum creatinine, and that the apparent steady-state volume of distribution of amikacin is slightly larger in patients with diminished renal function.
• It is essential to monitor serum amikacin concentrations and adjust the dose accordingly to avoid toxicity and ensure optimal drug concentrations, as suggested in 3, 5, 4, 6, 7.