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Amikacin

Amikacini sulfas

For medical students2 min readUpdated 2026-10-10

Amikacin is a semi-synthetic antibiotic belonging to the 3rd-generation aminoglycoside group. It serves as a reserve drug with the broadest spectrum of activity within its class, used for treating severe infections and tuberculosis.

Class3rd-generation aminoglycosides
MechanismInhibition of bacterial protein synthesis
RouteParenteral (intramuscular, intravenous)
StatusReserve drug (multidrug-resistant pathogens)

Chemical Structure and Origin

The chemical structure of all aminoglycosides is based on a cyclic alcohol (aminocyclitol) attached to aminosugars via glycosidic bonds. A key physicochemical property of these molecules is their high polarity.

Historically, drugs of this group are derived from natural sources—actinomycetes of the genera Actinomyces (yielding the suffix "-mycin") and Micromonospora (also yielding "-mycin"). However, amikacin is a semi-synthetic agent.

To understand the evolution of this class, it is important to remember the generational classification:

Mechanism of Action and Resistance Overcoming

The general mechanism of action for the entire aminoglycoside class is the inhibition of protein synthesis in the bacterial cell.

While drugs within the group share similar properties, they differ in activity spectra and resistance profiles. The key advantage of amikacin lies in its resistance-breaking mechanism: it is not inactivated by bacterial enzymes that degrade 2nd-generation aminoglycosides. Consequently, it successfully targets Gram-negative bacteria resistant to gentamicin or tobramycin.

Spectrum of Activity and Indications

Amikacin has the broadest spectrum of activity among all aminoglycosides. There are two primary directions for its clinical use:

  1. Severe Bacterial Infections: Prescribed for diseases caused by multidrug-resistant flora. The drug has a strict clinical status as a reserve medication. It is conserved and used restrictively to prevent the emergence of widespread microbial resistance.
  2. Tuberculosis: Amikacin is included among anti-tuberculosis antibiotics (along with streptomycin, kanamycin, rifampin, etc.). It exhibits specific activity against Mycobacterium avium. It is used for newly diagnosed pulmonary tuberculosis and extrapulmonary lesions.

Important: Mycobacterial resistance to aminoglycosides develops rapidly; therefore, they must always be used in combination with other anti-tuberculosis agents (both antibiotics and synthetic drugs like isoniazid or PAS).

Adverse Effects

Like other members of the class, amikacin exhibits significant toxicity. The primary concern is ototoxicity (damage to the auditory system). When selecting therapy, it is worth noting that among aminoglycosides, the 2nd-generation drug netilmicin exhibits the least pronounced ototoxic effect.

Formulation and Prescribing Guidelines

Due to high molecular polarity, aminoglycosides are practically unabsorbed in the gastrointestinal tract. Therefore, administration routes for amikacin are exclusively parenteral: intramuscular and intravenous.

The drug is available in vials containing 0.1, 0.5, and 1.0 g. The standard single dose is 0.5 g.

Prescription Example: Rp.: Amikacini sulfatis 0.5 D.t.d. N. 10 S. Intramuscularly 0.5 g twice daily (after dissolving in water for injection).

Mnemonic

Amikacin — an AMInoglycoside with Active Mycobacterium (Mycobacterium avium) protection. The Roman numeral III in "AmikacIIIn" highlights its 3rd generation.

Frequently asked questions

To which bacterial ribosomal subunit does amikacin bind to inhibit protein synthesis?

Amikacin binds to the 30S ribosomal subunit of bacteria. As an aminoglycoside, the drug first penetrates the bacterial cell wall via passive diffusion to reach this target. It is then actively transported across the cytoplasmic membrane into the cell. Ribosomal binding disrupts protein synthesis, producing the antibacterial effect.

What adverse effects, besides ototoxicity, are characteristic of amikacin?

In addition to ototoxicity, amikacin is associated with nephrotoxicity and vestibulotoxicity.

  • Nephrotoxicity: monitored via creatinine clearance and electrolyte levels; requires adequate hydration, correction of electrolyte imbalances, discontinuation of the injectable agent, and dose adjustment of other renally cleared drugs.
  • Vestibulotoxicity: may cause early symptoms such as transient dizziness and aural fullness, prompting dose reduction, an intermittent dosing schedule, otolaryngology consultation, and symptomatic therapy; discontinuation is necessary if symptoms persist or worsen.
Against which specific Gram-negative bacteria is amikacin most active?

Amikacin shows high activity against Pseudomonas aeruginosa and various Enterobacteriaceae.

  • Pseudomonas aeruginosa — high intrinsic activity, used in combination with other antibiotics.
  • Enterobacterales — includes Escherichia coli, Klebsiella species, and other pathogens.

Additionally, due to resistance to inactivating enzymes, amikacin effectively targets Gram-negative bacteria resistant to 2nd-generation aminoglycosides.

What are the absolute contraindications to amikacin administration?

An absolute contraindication to amikacin is diabetic nephropathy. Aminoglycoside antibiotics (including amikacin, gentamicin, tobramycin, and netilmicin) are strictly contraindicated in patients with diabetes mellitus, even with early signs of renal impairment. Renal excretory function must be assessed prior to systemically administering these antibiotics to such patients.

Which specific drugs are combined with amikacin in tuberculosis treatment?

In drug-resistant tuberculosis regimens, amikacin is classified as a group C second-line drug and may be included when regimens cannot be built using groups A and B alone.

For pediatric MDR-TB regimens, amikacin is listed among additional agents:

  • Pre-XDR TB: core drugs include bedaquiline, linezolid, cycloserine; additional second-line drugs include delamanid, amikacin, PAS, ethionamide/prothionamide, ethambutol, pyrazinamide, clofazimine.
  • XDR-TB: core drugs include linezolid/bedaquiline, cycloserine, delamanid, ethambutol, pyrazinamide; additional agents include meropenem + amoxicillin/clavulanate, ethionamide/prothionamide, PAS, amikacin, clofazimine.
Why is amikacin effective against bacteria resistant to gentamicin?

Amikacin is not hydrolyzed by bacterial enzymes that inactivate 2nd-generation aminoglycosides (such as gentamicin).

Can amikacin be administered orally in tablets?

No. Aminoglycoside molecules are highly polar and therefore not absorbed in the GI tract. The drug is administered exclusively via parenteral routes.

What is the clinical status of amikacin and why?

It is a reserve drug. It is prescribed only for severe infections caused by multidrug-resistant flora to prevent the development of global bacterial resistance.

How can rapid development of mycobacterial resistance to the drug be prevented?

When treating tuberculosis, amikacin (like streptomycin) must be used strictly in combination with other anti-tuberculosis agents.

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