Beta-Lactam Antiobiotics (Penicillins)

• What are the four main types of beta-lactam antibiotics?

  Penicillins, Cephalosporins, Carbapenems, Monobactams
• What is the chemical structure of penicillins composed of?

  Thiazolidine, Beta-lactam ring, Acyl side chain
• What is the mechanism of action (MoA) of penicillins?

  Penicillins bind to PBP and block transpeptidase, preventing peptidoglycan cross-linking
• What is the result of penicillins blocking transpeptidase?

  It prevents cross-linking of the peptidoglycan lattice, leading to a fragile cell wall
• What happens to bacteria when penicillins cause cell lysis?

  Bacteria release autolytic hydrolases, leading to cell death
• What type of antibiotic effect do penicillins have?

  Bactericidal and time-dependent
• What are the three main mechanisms of resistance to penicillins?

  Production of beta-lactamase, possession of defective PBP, and decreased permeability of the outer membrane
• What is an example of a potentiated penicillin?

  Clavulanic acid + amoxicillin = Augmentin
• What is the pharmacokinetics of penicillins regarding absorption?

  Oral absorption is very variable and depends on the degree of acid stability
• How are penicillins distributed in the body?

  Poorly distributed, mainly in extracellular fluid, and barely cross the blood-brain barrier except in meningitis
• How are penicillins eliminated from the body?

  Mainly by the kidneys with a half-life of 0.5-1 hour
• What are the therapeutic uses of penicillins?

  Effective against G+ve bacteria and first-line drugs for many infections, especially respiratory infections and UTIs
• What are the classifications of penicillins?

  Standard, Antistaphylococcal, Aminopenicillins, Antipseudomonal
• What are common adverse reactions to penicillins?

  Hypersensitivity reactions, including acute anaphylaxis and delayed anaphylaxis
• How should hypersensitivity reactions to penicillins be managed?

  Prompt intervention with epinephrine, antihistamines, and supportive measures
• What are some other adverse reactions associated with penicillins?

  Neutropenia, diarrhea, interstitial nephritis, increased liver enzymes, and decreased platelet function
• What are the key points regarding the pharmacokinetics of penicillins?

  • Absorption: Variable, depends on acid stability
  • Distribution: Poorly distributed, mainly in extracellular fluid, limited BBB penetration
  • Elimination: Primarily by kidneys, half-life of 0.5-1 hour
• What are the therapeutic uses and classifications of penicillins?

  • Therapeutic Uses:
  • Effective against G+ve bacteria
  • First-line drugs for respiratory infections and UTIs
  • Classifications:

  1. Standard (penicillin G & V)

  2. Antistaphylococcal (methicillin, nafcillin, etc.)

  3. Aminopenicillins (amoxicillin, ampicillin)

  4. Antipseudomonal (ticarcillin, piperacillin, etc.)
• Name some other potentiated penicillins

  Timentin

  Unasyn

  Tazact
• Name some highly acid-stable penicillins

  Flucloxacillin, ampicillin, cloxacillin, amoxicillin, phenethicillin (facaph)
• Name some moderately acid-stable penicillin

  penicillin v, oxacillin, nafcillin, carbenicillin (ponc)
• Name 2 least acid-stable penicillins

  penicillin G, methicillin
• What drugs prolong the elimination of penicillins?

  Probenecid and cephalosporins
• Mention a broad spectrum penicillin

  Aminopenicillin; amoxicillin and ampicillin