Download - Aminoglycosides antibiotics
AMINOGLY
COSIDES
ANTIBIO
TICS
Presented by:Swornim GyawaliRoll no :252010 batch
• Group of natural or semisynthetic antibiotics having
Glycosidic bond Glycosidic bond
Polybasic amino group
Amino
sugar
Amino
sugar
Streptidine2-deoxy
streptamineGarosamine
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.
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
THERAPEUTIC USES OF THE AMINOGLYCOSIDES
aminoglycoside
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,brucella,yersinia pestis,Calym.granulomatis
Gentamicin 3-5mg/kg/day or Divided in 3 doses 8 hrly
Respi infecion in critically ill,pseudomonas,proteus,meningitis,SABE
Ps.aeruginosa,proteus,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 oral0.3-0.5% topical
Infected wounds,burns,ulcers,conjunctivitis,external ear inf.
Gm –ve bacilli and some Gm+ve cocci
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
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.