Can Amikacin (antibiotic) intramuscular (IM) injection be diluted with lidocaine (local anesthetic)?

Amikacin IM Injection with Lidocaine Dilution

Amikacin intramuscular (IM) injections can be diluted with lidocaine to reduce injection pain without affecting the antibiotic's pharmacokinetics or efficacy.

Evidence for Lidocaine Dilution with Amikacin

The coadministration of lidocaine with amikacin for IM injections has been studied specifically in children with multidrug-resistant tuberculosis, showing:

• Significantly reduced pain scores immediately after injection (median 1.0 with lidocaine vs 2.5 without) 1
• No significant changes in amikacin's pharmacokinetic parameters:
  • Area under the concentration time curve remained similar (109.0 μg×h/mL with lidocaine vs 103.3 μg×h/mL without) 1
  • Maximum plasma concentration was not significantly altered (36.7 μg/mL with lidocaine vs 34.1 μg/mL) 1

Recommended Administration Technique

When diluting amikacin with lidocaine for IM administration:

1. Use the appropriate amikacin dose based on patient characteristics:

   • Adults: 15 mg/kg/day (maximum 1.0 g/day) as a single daily dose 2
   • Adults over 59 years: 10 mg/kg/day (maximum 750 mg) 2
   • Children: 15-30 mg/kg/day as a single daily dose (maximum 1 g/day) 2

2. For lidocaine dilution:

   • Use 0.2-0.4 mg/kg of lidocaine based on the pediatric study protocol 1
   • Ensure the total volume is appropriate for IM administration

Important Considerations and Precautions

Contraindications for Lidocaine Use

• Hypersensitivity to lidocaine or other amide-type local anesthetics
• Myasthenia gravis (amikacin may impair neuromuscular transmission) 3
• Severe heart block or severe degrees of sinoatrial, atrioventricular, or intraventricular block

Monitoring Requirements

• Regular assessment of renal function (monthly) 3
• Auditory and vestibular monitoring (baseline and periodically) 3
• Serum amikacin levels when appropriate (target trough <5 mg/L) 3

Drug Interactions

• Do not use amikacin simultaneously with other aminoglycosides (capreomycin, kanamycin, or streptomycin) 3
• Increased risk of ototoxicity when used with loop diuretics 3
• Increased risk of nephrotoxicity with other nephrotoxic agents 3

Clinical Pearls

1. Lidocaine dilution is particularly beneficial for patients requiring repeated IM injections of amikacin, such as in tuberculosis treatment regimens.

2. The pain reduction benefit is most pronounced immediately after injection and can significantly improve patient comfort and adherence to treatment.

3. For ophthalmologic infections, IM amikacin can achieve therapeutic aqueous humor levels (average 1.0 mg/L after single dose, 3.5 mg/L after two doses) 4, which is sufficient for most gram-negative pathogens.

4. When preparing amikacin for IM injection, standard concentration and formulation should be used consistently to reduce the risk of errors.

5. For patients with renal impairment, the dosing frequency should be reduced, but the milligram dose should be maintained at 12-15 mg/kg per dose to ensure efficacy 3.