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.