Pharmacology
Mechanism of action
Amikacin irreversibly binds to 16S rRNA and the RNA-binding S12 protein of the 30S subunit of prokaryotic ribosome and inhibits protein synthesis by changing the ribosomes shape so that it cannot read the mRNA codons correctly. It also interferes with the region that interacts with the wobble base of the tRNA anticodon. It works in a concentration-dependent manner, and has better action in an alkaline environment.At normal doses, amikacin-sensitive bacteria respond within 24–48 hours. Resistance
Amikacin evades attacks by all antibiotic-inactivating enzymes that are responsible for antibiotic resistance in bacteria, except for aminoacetyltransferase and nucleotidyltransferase. This is accomplished by the L-hydroxyaminobuteroyl amide (L-HABA) moiety attached to N-1 (compare to kanamycin, which simply has a hydrogen), which blocks the access and decreases the affinity of aminoglycoside-inactivating enzymes. Amikacin ends up with only one site where these enzymes can attack, while gentamicin and tobramycin have six.Bacteria that are resistant to streptomycin and capreomycin are still susceptible to amikacin; bacteria that are resistant to kanamycin have varying susceptibility to amikacin. Resistance to amikacin also confers resistance to kanamycin and capreomycin.Resistance to amikacin and kanamycin in Mycobacterium, the causative agent of tuberculosis, is due to a mutation in the rrs gene, which codes for the 16S rRNA. Mutations such as these reduce the binding affinity of amikacin to the bacterias ribosome.
Amikacin is also injected into the joints with the anti-arthritic medication Adequan in order to prevent infection.Side effects in animals include nephrotoxicity, ototoxicity, and allergic reactions at IM injection sites. Cats tend to be more sensitive to the vestibular damage caused by ototoxicity. Less frequent side effects include neuromuscular blockade, facial edema, and peripheral neuropathy.The half-life in most animals is one to two hours.Treating overdoses of amikacin requires kidney dialysis or peritoneal dialysis, which reduce serum concentrations of amikacin, and/or penicillins, some of which can form complexes with amikacin that deactivate it. Liposome inhalation suspension
Amikacin liposome inhalation suspension was the first drug approved under the US limited population pathway for antibacterial and antifungal drugs (LPAD pathway). It also was approved under the accelerated approval pathway. The U.S. Food and Drug Administration (FDA) granted the application for amikacin liposome inhalation suspension fast track, breakthrough therapy, priority review, and qualified infectious disease product (QIDP) designations. The FDA granted approval of Arikayce to Insmed, Inc.The safety and efficacy of amikacin liposome inhalation suspension, an inhaled treatment taken through a nebulizer, was demonstrated in a randomized, controlled clinical trial where patients were assigned to one of two treatment groups. One group of patients received amikacin liposome inhalation suspension plus a background multi-drug antibacterial regimen, while the other treatment group received a background multi-drug antibacterial regimen alone.