Amikacin Dosing Recommendations
Adults with Normal Renal Function
For adults with normal renal function, administer amikacin 15 mg/kg once daily (maximum 1.5 g/day) as an IV infusion over 30–60 minutes. 1
- Once-daily dosing is preferred for 5–7 days per week during initial treatment, as it achieves superior peak concentrations and lower trough levels compared to divided dosing 1, 2
- Alternative divided-dose regimens include 7.5 mg/kg every 12 hours or 5 mg/kg every 8 hours, though these are less optimal 1
- For complicated intra-abdominal infections specifically, use 15–20 mg/kg once daily with therapeutic drug monitoring 1
- After 2–4 months of therapy or culture conversion (in tuberculosis treatment), reduce frequency to 15–25 mg/kg three times weekly 1
Critical caveat: Standard unmonitored dosing places 6% of patients at risk for toxicity; therapeutic drug monitoring is essential and routine standard dosing without monitoring cannot be recommended 3
Elderly Patients (>59 Years)
Reduce the dose to 10 mg/kg once daily (maximum 750 mg) in patients over 59 years of age to minimize ototoxicity and nephrotoxicity risk. 1, 4
- Elderly patients frequently have reduced creatinine clearance even when serum creatinine appears normal, necessitating dose reduction 5
- The lower dose of 11 mg/kg has been shown safe and practical in elderly populations 5
- Monthly monitoring of renal function and auditory/vestibular symptoms is mandatory 1, 4
Patients with Renal Impairment
Never reduce the mg/kg dose in renal impairment; instead extend the dosing interval to preserve concentration-dependent bactericidal activity. 1, 6
Dosing Algorithm by CKD Stage:
- Stage 3A (GFR 40–59 mL/min): 7.5 mg/kg once daily 6
- Stage 3B (GFR 30–39 mL/min): 4 mg/kg once daily 6
- Stage 4 (GFR 15–29 mL/min): 4 mg/kg once daily OR 6 mg/kg every 48 hours 6
- Daily dosing is more effective than every-other-day dosing in stage 4 CKD due to higher trough levels (6.9 vs 1.9 mcg/mL) and better bacterial eradication 6
- Stage 5 on hemodialysis: 12–15 mg/kg administered 2–3 times weekly after dialysis 1, 7
- Hemodialysis reduces amikacin half-life from 28 hours to 3.75 hours, requiring post-dialysis dosing 7
- Stage 5 on peritoneal dialysis: 4 mg/kg every 48 hours 6
- Peritoneal dialysis has minimal effect on amikacin clearance (half-life remains ~29 hours) 7
Practical Interval Calculation:
- Multiply serum creatinine (mg/dL) by 9 to obtain dosing interval in hours 1
- Example: creatinine 2 mg/dL → dose every 18 hours 1
Monitoring is critical: Trough levels are directly associated with therapeutic efficacy in CKD patients; inadequate troughs lead to treatment failure 6
Obese Patients
Calculate dosing weight as ideal body weight (IBW) + 40% of excess weight. 1
IBW Formulas:
Male: 50 kg + 2.3 × [(height in cm − 152.4) ÷ 2.54] 1
Female: 45.5 kg + 2.3 × [(height in cm − 152.4) ÷ 2.54] 1
For complicated intra-abdominal infections in obese patients, base dosing on lean body mass and estimated extracellular fluid volume rather than total body weight 1
Avoid using fixed 500 mg doses regardless of weight, as this causes underdosing and treatment failure 1
Pediatric Patients
For children and older infants, administer 15–30 mg/kg once daily (maximum 1 g/day). 1, 4
Age-Specific Pharmacokinetics:
- Infants <6 months have larger volume of distribution (0.58 L/kg) and prolonged half-life (5.02 hours) compared to adults (0.33 L/kg, 3.45 hours) 2
- Infants 6–12 months have intermediate parameters (Vd 0.50 L/kg, half-life 2.86 hours) 2
- Once-daily dosing achieves therapeutic peaks in 100% of pediatric patients versus only 44% with twice-daily dosing 2
Critical consideration: Pharmacokinetic parameters vary by a factor of 6–10 within pediatric age groups, making therapeutic drug monitoring essential 2
Therapeutic Drug Monitoring
Target Concentrations:
- Peak for daily dosing: 25–35 mg/L 1
- Peak for thrice-weekly dosing: 65–80 mg/L 1
- Trough: <5 mg/L to prevent toxicity 1
Sampling Timing:
Monitoring Frequency:
- Measure peak during first week; repeat if clinical response is poor 1
- Check trough weekly for first 4 weeks, then every 2 weeks once stable 1
- Monitor renal function twice weekly in month 1, weekly in month 2, then fortnightly thereafter 1
Safety Monitoring and Contraindications
Baseline Assessment:
Toxicity Risks:
- Ototoxicity: Occurs in 1.5–24% of patients; defined as 20 dB loss at any frequency or 10 dB loss at two adjacent frequencies 1
- Nephrotoxicity: Occurs in 8.7% overall but only 3.4% in patients without risk factors 1
- Concurrent loop diuretics markedly increase ototoxicity risk 1