Aminoglycosides are a class of antibiotics that were discovered in 1944 and are produced by Streptomyces and Micromonospora bacteria. They include streptomycin, gentamicin, kanamycin, tobramycin, and amikacin for systemic use, as well as neomycin and framycetin for topical use. Aminoglycosides are highly polar, administered parenterally, distributed extracellularly, and excreted unchanged in urine. They are bactericidal against aerobic gram-negative bacilli by inhibiting bacterial protein synthesis. While effective against various infections, aminoglycosides can cause ototoxicity, nephrotoxicity, and neuromuscular blockade

1. AMINOGLYCOSIDES

2.  Waksman in 1944 – discovered Streptomycin
 Source :
Streptomyces – ‘ mycins’ ( e.g. Streptomycin)
Micromonospora – ‘micins’ (e.g. Gentamicin)

3. Classification
Systemic aminoglycosides
• Streptomycin
• Gentamicin
• Kanamycin
• Tobramycin
• Amikacin
Topical aminoglycosides
• Neomycin
• Framycetin

4. Common properties of aminoglycosides
1. Consists of two or more amino sugars joined
to a hexose nucleus by glycosidic linkage.
2. Highly polar – administered parenterally for
systemic effect.
3. Distributed extracellularly , do not penetrate
brain or CSF.
4. Excreted unchanged in urine by glomerular
filtration (t1/2 – 2 to 3 hrs).

5. 5. Bactericidal action – aerobic gram negative bacilli.
6. Acts by inhibiting bacterial protein synthesis.
7. There is partial cross-resistance among them.
8. Exhibits ototoxicity & nephrotoxicity.
9. Transport of aminoglycosides into the bacterial cell
requires oxygen – anaerobes are resistant.
10. Exhibits synergism when combined with β-lactam
antibiotics.

6. Therapeutic uses
 Urinary tract infections
 Bacterial endocarditis
 Tuberculosis
 Plague
 Tularemia
 Brucellosis
Topical use
Gentamicin, tobramycin, neomycin, framycetin
– gram –ve skin, eye and ear infections

7. Adverse effects
1.Ototoxicity
Cochlear & vestibular damage
2. Nephrotoxicity – reversible
3.Neuromuscular blockade
• inhibits Ach release from the motor nerve
endings
• apnoea, paralysis

8. 4.Hypersensitivity reactions
5.Local irritation
pain, paresis, respiratory depression,
nystagmus & convulsions
6. Superinfection

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