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Aminoglycosides antibiotics

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Aminoglycosides antibiotics

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Aminoglycosides antibiotics

  1. 1. Presented by: Swornim Gyawali Roll no :25 2010 batch
  2. 2. • Group of natural or semisynthetic antibiotics having Glycosidic bond Glycosidic bond Polybasic amino group Amino sugar Amino sugar Streptidine 2-deoxy streptamine Garosamine
  3. 3. CLASSIFICATION Systemic Topical • Streptomycin Neomycin • Gentamycin Framycetin • Kanamycin • Tobramycin • Amikacin • Sisomicin • Netilmicin Note:  all derived from soil actinomycetes  Not absorbed orally, excreted unchanged in urine  Primarily active against aerobic gm –ve bacilli.
  4. 4. MECHANISM OF ACTION: • Bactericidal antibiotics • Two main steps: a) Transport of the aminoglycosides through bacterial cell wall & cytoplasmic membrane (diffusion-outer coat-Gm –ve via porin channel) b) Irreversibly Binding to ribosomes (mostly 30s and 50s,30s &50s interface) resulting in inhibition of protein synthesis. Note : cidial action is concentration dependent i.e rate of bacterial cell killing is directly realted to the ratio of peak antibiotic concn to the MIC value
  5. 5. THERAPEUTIC USES OF THE AMINOGLYCOSIDES aminoglycosi de doses uses Active against Streptomycin 1g or 0.75g i.m BD*7 TB : 1g 1/2 wkly 2months TB,SABE, Urinary tract infections, peritonitis, septicemias M.tuberculosis,brucell a,yersinia pestis,Calym.granulo matis Gentamicin 3-5mg/kg/day or Divided in 3 doses 8 hrly Respi infecion in critically ill,pseudomonas,proteu s,meningitis,SABE Ps.aeruginosa,proteu s,e.coli,klebsiella Tobramycin 3-5mg/kg/day in 1-3 doses Gram negative infections, Pseudomonas Pseudomonas, proteus Amikacin 3-5mg/kg/day in 1-3 doses Pseudomonas ,proteus and staph. infections Pseudomonas ,proteus and staph. Neomycin 0.25-1g QID oral 0.3-0.5% topical Infected wounds,burns,ulcers,co njunctivitis,external ear Gm –ve bacilli and some Gm+ve cocci
  6. 6. TOXICITY: • Ototoxicity: concentrated in labrinthine fluid • Nephrotoxicity : attain high concn. In renal cortex • Neuromuscular blockage: reduce Ach release • Contact dermatitis Contraindication: • Perforated ear drum • Pregnancy :foetal toxicity • Kidney damage person
  7. 7. TAKE HOME MESSAGE: 1. All are sulfate salts which are highly soluble in water and solutions are stable for months 2. They ionize in solution, not absorbed orally, distribute only extracellularly and do not penetrate in brain and CSF 3. All are excreted unchanged in urine 4. All are bactericidal and more active at alkaline pH 5. Act by interfering bacterial protein synthesis 6. Active against aerobic gm –ve bacteria, but spectrum differs 7. Partial cross resistance, organisms resistant to one amino glycoside may still respond to another 8. Narrow margin of safety 9. All exhibit ototoxity and nephrotoxicity.

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