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Title: Neomycin  
Author: World Heritage Encyclopedia
Language: English
Subject: Amphotericin B, Tetracycline, Doxycycline, Aminoglycoside, Streptomycin
Collection: Aminoglycoside Antibiotics, Otologicals
Publisher: World Heritage Encyclopedia


Systematic (IUPAC) name
Clinical data
Trade names Neo-rx
  • US: D (Evidence of risk)
Legal status
Routes of
Topical, Oral
Pharmacokinetic data
Bioavailability 0% Oral, Unknown Topical,
Protein binding N/A
Metabolism N/A
Biological half-life 2 to 3 hours
CAS Registry Number  Y
ATC code A01 A07, B05, D06, J01, R02, S01, S02, S03
PubChem CID:
DrugBank  Y
ChemSpider  Y
Synonyms Framycetin
Chemical data
Formula C23H46N6O13
Molecular mass 614.644 g/mol

Neomycin is an aminoglycoside antibiotic found in many topical medications such as creams, ointments, and eyedrops. The discovery of neomycin dates back to 1949. It was discovered in the lab of Selman Waksman, who was later awarded the Nobel Prize in Physiology or Medicine in 1951. Neomycin belongs to aminoglycoside class of antibiotics that contain two or more aminosugars connected by glycosidic bonds. Due to the inherent oto- and nephrotoxicity of these substances, systemic use has declined, as safer alternatives have become available.


  • Uses 1
  • Molecular biology 2
  • Spectrum 3
  • Composition 4
  • Safety 5
  • History 6
  • DNA binding 7
  • References 8


Neomycin is typically used as a topical preparation, such as Neosporin. It can also be given orally, where it is usually combined with other antibiotics. Neomycin is not absorbed from the gastrointestinal tract and has been used as a preventive measure for hepatic encephalopathy and hypercholesterolemia. By killing bacteria in the intestinal tract, it keeps ammonia levels low and prevents hepatic encephalopathy, especially prior to GI surgery. It has also been used to treat small intestinal bacterial overgrowth. It is not given via injection, as neomycin is extremely nephrotoxic (causes kidney damage), even when compared to other aminoglycosides. The exception is when neomycin is included, in very small quantities, as a preservative in some vaccines – typically 0.025 mg per dose.[1]

Molecular biology

Neomycin resistance is conferred by either one of two aminoglycoside phosphotransferase genes.[2] A neo gene is commonly included in DNA plasmids used by molecular biologists to establish stable mammalian cell lines expressing cloned proteins in culture; many commercially available protein expression plasmids contain neo as a selectable marker. Non-transfected cells will eventually die off when the culture is treated with neomycin or similar antibiotic. Neomycin or kanamycin can be used for prokaryotes, but geneticin (G418) is, in general, needed for eukaryotes.


Similar to other aminoglycosides, neomycin has excellent activity against Gram-negative bacteria, and has partial activity against Gram-positive bacteria. It is relatively toxic to humans, and many people have allergic reactions to it.[3] See: Hypersensitivity. Physicians sometimes recommend using antibiotic ointments without neomycin, such as Polysporin.[4] The following represents MIC susceptibility data for a few medically significant Gram-negative bacteria.

  • Enterobacter cloacae: >16 μg/ml
  • Escherichia coli: 1 μg/ml
  • Proteus vulgaris: 0.25 μg/ml



Standard grade neomycin is composed of a number of related compounds including neomycin A (neamine), neomycin B (framycetin), neomycin C, and a few minor compounds found in much lower quantities. Neomycin B is the most active component in neomycin followed by neomycin C and neomycin A. Neomycin A is not a unique structure, but rather a compositional degradation product of the C and B isomers.[6] The quantities of these components in neomycin vary from lot-to-lot depending on the manufacturer and manufacturing process.[7]


In 2005–06, neomycin was the fifth-most-prevalent allergen in patch test results (10.0%).[8]


Neomycin was discovered in 1949 by the microbiologist Selman Waksman and his student Hubert Lechevalier at Rutgers University. It is produced naturally by the bacterium Streptomyces fradiae.[9] Synthesis requires specific nutrient conditions in either stationary or submerged aerobic conditions. The compound is then isolated and purified from the bacterium.[10]

DNA binding

Aminoglycosides such as neomycin are known for their ability to bind to duplex RNA with high affinity. The association constant for neomycin with A-site RNA has been found to be in the 109 M−1 range.[11] However, more than 50 years after its discovery, its DNA-binding properties were still unknown. Neomycin has been shown to induce thermal stabilization of triplex DNA, while having little or almost no effect on the B-DNA duplex stabilization.[12] Neomycin was also shown to bind to structures that adopt A-form structure, triplex DNA being one of them. Neomycin also includes DNA:RNA hybrid triplex formation.[13]


  1. ^ "Medscape article". 
  2. ^ "G418/neomycin-cross resistance?". Retrieved 2008-10-19. 
  3. ^ DermNet dermatitis/neomycin-allergy
  4. ^ "Your Medicine Cabinet"., Inc. Retrieved 2008-10-19. 
  5. ^
  6. ^ Cammack, R. Attwood, T. K. Campbell, P. N. Parish, J. H. Smith, A. D. Stirling, J. L. Vella, F. (2006). "Oxford Dictionary of Biochemistry and Molecular Biology (2nd Edition) – neomycin." Oxford University Press. (2006): 453. Web. 18 Nov. 2014.
  7. ^ Tsuji, Kiyoshi, and John H. Robertson. "Comparative Study of Responses to Neomycins B and C by Microbiological and Gas-Liquid Chromatographic Assay Methods."Applied Microbiology 18.3 (1969): 396–98. Web. 23 Oct. 2013.
  8. ^ Zug KA, Warshaw EM, Fowler JF Jr, Maibach HI, Belsito DL, Pratt MD, Sasseville D, Storrs FJ, Taylor JS, Mathias CG, Deleo VA, Rietschel RL, Marks J. Patch-test results of the North American Contact Dermatitis Group 2005–2006. Dermatitis. 2009 May–Jun;20(3):149-60.
  9. ^ "The Nobel Prize in Physiology or Medicine 1952". Nobel Foundation. Retrieved 2008-10-29. 
  10. ^ "Neomycin." Pharmaceutical Manufacturing Encyclopedia (3rd edition) Volume 3. (2007): 2415–2416. Web. 18 Nov. 2014.
  11. ^ "Thermodynamics of aminoglycoside-rRNA recognition: the binding of neomycin-class aminoglycosides to the A site of 16S rRNA". 
  12. ^ "DNA Triple Helix Stabilization by Aminoglycoside Antibiotics". 
  13. ^ "Neomycin-induced hybrid triplex formation". 
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