amikasin

Amikacin, sometimes spelled amikasin in some sources, is an aminoglycoside antibiotic developed as a semi-synthetic derivative of kanamycin A. It is produced by Streptomyces kanamyceticus and is used to treat various severe bacterial infections.

Mechanism of action: Amikacin binds irreversibly to the 30S ribosomal subunit, causing misreading of messenger RNA and blocking initiation of protein synthesis. This leads to a bactericidal effect, particularly against Gram-negative bacteria.

Spectrum and uses: It has broad activity against many Gram-negative organisms, including Pseudomonas aeruginosa and many Enterobacterales. Amikacin is relatively resistant to inactivation by many aminoglycoside-modifying enzymes, making it useful for strains resistant to other aminoglycosides. It has limited activity against most Gram-positive bacteria and is ineffective against anaerobes. It is typically used for serious infections such as septicemia, complicated urinary tract infections, intra-abdominal infections, hospital-acquired pneumonias, and infections due to multi-drug resistant Gram-negative bacteria, often in combination with a beta-lactam or other agents for synergy.

Administration and pharmacokinetics: Amikacin is given parenterally (intravenous or intramuscular). It is poorly absorbed from the gastrointestinal tract. It distributes into body fluids and tissues and is predominantly excreted unchanged by the kidneys. Dosing must be adjusted in renal impairment, and therapeutic drug monitoring of trough levels (and sometimes peak levels) is commonly used to balance efficacy and toxicity.

Adverse effects and safety: The main toxicities are nephrotoxicity and ototoxicity (cochlear and vestibular), which can be irreversible. Neuromuscular blockade is possible. Caution is advised with other nephrotoxic or ototoxic drugs; use is generally avoided in pregnancy unless clearly necessary.

Resistance: Bacteria may develop resistance via aminoglycoside-modifying enzymes or 16S rRNA methyltransferases, reducing amikacin activity.