Chemistry
Amikacin is derived from kanamycin A:

Veterinary use
While amikacin is only FDA-approved for use in dogs and for intrauterine infection in horses, it is one of the most common aminoglycosides used in veterinary medicine, and has been used in dogs, cats, guinea pigs, chinchillas, hamsters, rats, mice, prairie dogs, cattle, birds, snakes, turtles and tortoises, crocodilians, bullfrogs, and fish. It is often used for respiratory infections in snakes, bacterial shell disease in turtles, and sinusitis in macaws. It is generally contraindicated in rabbits and hares (though it has still been used) because it harms the balance of intestinal microflora.In dogs and cats, amikacin is commonly used as a topical antibiotic for ear infections and for corneal ulcers, especially those that are caused by Pseudomonas aeruginosa. The ears are often cleaned before administering the medication, since pus and cellular debris lessen the activity of amikacin. Amikacin is administered to the eye when prepared as an ophthalmic ointment or solution, or when injected subconjunctivally. Amikacin in the eye can be accompanied by cephazolin. Despite its use there amikacin (and all aminoglycosides) are toxic to intraocular structures.In horses, amikacin is FDA-approved for uterine infections (such as endometriosis and pyometra) when caused by susceptible bacteria. It is also used in topical medication for the eyes and arthroscopic lavage; when combined with a cephalosporin, is used to treat subcutaneous infections that are caused by Staphylococcus. For infections in the limbs or joints, it is often administered with a cephalosporin via limb perfusion directly into the limb or injected into the joint.
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.