Thursday, 26 February 2015

AMINOGLYCLOSIDE

Mechanism:
         They bind on 30S ribosome and does the following actions :
  1. Inhibition of formation of initiation complex
  2. Inhibition of polysome formation 
  3. Misreading of mRNA
DRUGS:
  1. Streptomycin
  2. Gentamicin
  3. Tobramycin
  4. Amikacin
  5. Neomycin
PHARMACOKINETICS:
  1. They are given parenterally, topically, orally[but not absorbed by GI tract].
  2. They are not metabolized in body.
  3. They are excreted unchanged in urine.
  4. They do not cross blood brain barrier.
USE:
  1. Active against all GRAM -VE organisms
  2. Active against GRAM +VE , if used in combination with BETA-LACTAMS or VANCOMYCIN.
  3. Streptomycin is used as 1st line drug in TB
    Drug of choice in tularemia and plague
  4. Amikacin is 2nd line drug in TB.
  5. Neomycin used orally for gut sterilization.Neomycin used topically for skin infections.
  6. Spectinomycin used in treating PENICILLINASE-PRODUCING Neisseria gonnorhoea [PPNG].
ADVERSE EFFECTS:
  1. OTOTOXICITY:
                  Amikacin, Neomycin causes hearing loss.
                  Gentamicin , Streptomycin causes vestibular toxicity.
                  Tobramycin causes both.
  2. NEPHROTOXICITY:               Neomycin is most Nephrotoxic and not given I.V
                   Gentamycin is most toxic drug given as I.V
                   Streptomycin is the least toxic.
  3. NEURO-MUSCULAR BLOCKADE:
                   These drugs decrease the release of Ach as well as decrease the senstivity of post-synaptic membrane.
    Hence should not be administered in case of Hypocalcemia, Respiratory depression and Neuromuscular blockers .

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