Gentamicin A is a component of the antibiotic gentamicin. This antibiotic is composed by members of the gentamicin C complex (80%) and gentamicin A, B, X, and others (remaining 20%). A review study from 2018 indicated that acute kidney injury was described in 2520 participants receiving gentamicin, which contains gentamicin A. Most of these cases were reversible. Also, a rise in creatinine levels was found in some patients after administration of a single dose of gentamicin.

Sisomicin is a new broad-spectrum aminoglycoside most closely related structurally to gentamicin C1a. In vitro and in experimental infections, sisomicin has been found to be more potent than or nearly as potent as the most active of the other available aminoglycosides. Although susceptible to many (but not all) aminoglycoside-inactivating enzymes, sisomicin is active against many microorganisms that are resistant to other aminoglycosides by nonenzymatic mechanisms. Sisomicin has been shown to interact synergistically with various beta-lactam antibiotics against enterococci, staphylocicci, Enterobacteriaceae, and nonfermentative gram-negative bacilli. The pharmacokinetics and toxicity of sisomicin in humans appear to be similar to those of gentamicin, despite earlier reports of greater acute toxicity in animals. Sisomicin binds to 30s and 50s ribosomal subunits of susceptible bacteria disrupting protein synthesis, thus rendering the bacterial cell membrane defective.

Micronomicin is a new aminoglycosidic antibiotic discovered and developed by Kyowa Hakko Kogyo Co., Ltd. It is produced by Micromonospora sagamiensis var. nonreducans. Investigation of micronomicin performed in 134 research facilities in Japan led to the following results. 1) Micronomicin showed a broad antibacterial spectrum against Gram positive and Gram negative bacteria. 2) In susceptibility tests of clinical isolates, micronomicin was almost similarly active to GM. 3) Bactericidal activity of micronomicin against Pseudomonas aeruginosa and E. coli was higher than those of TOB and DKB. 4) Micronomicin showed a synergistic antibacterial activity against Pseudomonas aeruginosa and E. coli with CBPC and SBPC. 5) The therapeutic activity of micronomicin in mice infected with Pseudomonas aeruginosa and Serratia sp. was in high correlation with in vitro antibacterial activity similarly to that of GM. Micronomicin (sold under the brand names Sagamicin and Luxomicina among others) is an aminoglycoside antibiotic, and like others in its class, binds to the ribosomes of non-resistant cells causing mistranscription of mRNA which fatally inhibits production of essential proteins. Micronomicin sulfate can inhibit bacterial protein synthesis, while destroy the bacterial cell wall. Micronomicin has an antibacterial activity against gram-negative and gram-positive bacteria such as Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Shara, Escherichia coli, etc. Streptococcus pneumoniae and Pneumococcus are sensitive to it, but its activity on anaerobic bacteria and some hemolytic streptococcus is weak.

Gentamicin is an antibiotic of the aminoglycoside group, is derived from the growth of Micromonospora purpurea, an actinomycete. Gentamicin is a complex of three different closely related aminoglycoside sulfates, Gentamicins C1, C2, and C1a that have different patterns of methylation at the 69 position of the ring. Gentamicin C1a is a broad-spectrum antibiotic against Gram-positive and Gram-negative bacteria but may cause ear and kidney damage. Gentamicin C1a binds to the A-site RNA of the 30S bacterial ribosomal subunit. Adverse reactions include adverse renal effects, neurotoxicity (dizziness, vertigo, tinnitus, roaring in the ears, hearing loss, peripheral neuropathy or encephalopathy), respiratory depression, lethargy, confusion, depression, visual disturbances, etc.

Isepamicin is an aminoglycoside antibacterial with properties similar to those of amikacin, but with better activity against strains producing type I 6'-acetyltransferase. The antibacterial spectrum includes Enterobacteriaceae and staphylococci. Anaerobes, Neisseriaceae and streptococci are resistant. The lower and upper break-points are 8 and 16 mg/L. Like other aminoglycosides, isepamicin exhibits a strong concentration-dependent bactericidal effect, a long post-antibiotic effect (several hours) and induces adaptive resistance. Isepamicin is administered intravenously or intramuscularly at a dosage of 15 mg/kg once daily or 7.5 mg/kg twice daily. Isepamicin is not bound to plasma proteins, and it distributes in extracellular fluids and into some cells (outer hair cells, kidney cortex) by active transport. Isepamicin has been developed and approved for clinical use in the 1990s.

Gentamicin C1 is a part of gentamicin C complex, containing gentamicin C1, gentamicin C1a, and gentamicin C2 which compose approximately 80% of gentamicin and have been found to have the highest antibacterial activity. Commercial gentamicin C is a mixture of gentamicin C1, C1a, and C2. Gentamicin C1 has a methyl group in the 6' position of the 2-amino-hexose ring and is N methylated at the same position. Gentamicin is a broad spectrum aminoglycoside antibiotic. Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth. Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis. Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses. Aminoglycosides like gentamicin "irreversibly" bind to specific 30S-subunit proteins and 16S rRNA. Specifically gentamicin binds to four nucleotides of 16S rRNA and a single amino acid of protein S12. This interferes with decoding site in the vicinity of nucleotide 1400 in 16S rRNA of 30S subunit. This region interacts with the wobble base in the anticodon of tRNA. This leads to interference with the initiation complex, misreading of mRNA so incorrect amino acids are inserted into the polypeptide leading to nonfunctional or toxic peptides and the breakup of polysomes into nonfunctional monosomes. Gentamicin complex is used for treatment of serious infections caused by susceptible strains of the following microorganisms: P. aeruginosa, Proteus species (indole-positive and indole-negative), E. coli, Klebsiella-Enterobactor-Serratia species, Citrobacter species and Staphylococcus species (coagulase-positive and coagulase-negative).