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Patrick

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Patrick An Introduction to Medicinal Chemistry 3/e Chapter 16 ANTIBACTERIAL AGENTS Part 3: Other lactams Newer b-Lactam Antibiotics Thienamycin (Merck 1976)(from ... – PowerPoint PPT presentation

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Title: Patrick


1
Patrick An Introduction to Medicinal Chemistry
3/e Chapter 16 ANTIBACTERIAL AGENTS Part 3
Other lactams
2
Newer b-Lactam Antibiotics
Thienamycin (Merck 1976)(from Streptomyces
cattleya)
  • Potent and wide range of activity vs Gram ve and
    Gram -ve bacteria
  • Active vs. Pseudomonas aeruginosa
  • Low toxicity
  • High resistance to b-lactamases
  • Poor stability in solution (ten times less stable
    than Pen G)

3
Newer b-Lactam Antibiotics
Thienamycin analogues used in the clinic
4
Newer b-Lactam Antibiotics
Nocardicins (Fujisawa 1975)
  • Monocyclic b-lactam ring - monobactams
  • Moderately active in vitro vs narrow group of
    Gram -ve bacteria
  • Active vs. Pseusomonas aeruginosa
  • Inactive vs. Gram ve bacteria
  • Different spectrum of activity from penicillins
  • Thought to operate by a different mechanism from
    penicillins
  • Low toxicity

5
Newer b-Lactam Antibiotics
Clinically useful monobactam
  • Administered by intravenous injection
  • Can be used for patients with allergies to
    penicillins
  • and cephalosporins
  • No activity vs. Gram ve or anaerobic bacteria
  • Active vs. Gram -ve aerobic bacteria

6
b-Lactamase Inhibitors
Clavulanic acid (Beechams 1976)(from Streptomyces
clavuligerus)
  • Weak, unimportant antibacterial activity
  • Powerful irreversible inhibitor of b-lactamases -
    suicide substrate
  • Used as a sentry drug for ampicillin
  • Augmentin ampicillin clavulanic acid
  • Allows less ampicillin per dose and an increased
    activity spectrum
  • Timentin ticarcillin clavulanic acid

7
b-Lactamase Inhibitors
Clavulanic acid - mechanism of action
8
b-Lactamase Inhibitors
Penicillanic acid sulfone derivatives
  • Suicide substrates for b-lactamase enzymes
  • Sulbactam has a broader spectrum of activity vs
    b-lactamases than clavulanic acid, but is less
    potent
  • Unasyn ampicillin sulbactam
  • Tazobactam has a broader spectrum of activity vs
    b-lactamases than clavulanic acid, and has
    similar potency
  • Tazocin or Zosyn piperacillin tazobactam
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