Penicillinase Stable Penicillins

Penicillins (β-Lactams Antibiotics)
They are called Penicillinase Stable because they resist the Staphylococcus produced β-Lactamase

Drugs:

• Acid Sensitive: Impractical to use (damaged by gastric acids)
  • Methicillin
• Acid Resistant (In increasing lipophilicity order): most contain Halogen compounds
  • Oxacillin
  • Cloxacillin
  • Dicloxacillin
  • Flucloxacillin
  • Nafcillin

Antibacterial spectrum: Similar to 1st Generation Cephalosporins

• Most Gr+ bacteria:
  • All the Gr+ bacteria covered by Narrow Spectrum Penicillins
    • Including Streptococcus
  • • Staphylococcus
• No Gr- bacteria

Pharmacokinetics:

• The Penicillinase Stable Penicillins don’t cross the Blood Milk Barrier
  • They stay concentrated in the mammary ducts and don’t enter the bloodstream
  • The more lipophilic the easier they are washed out in the milk

Indication:

• Mastitis (Staphylococcus, Streptococcus): Intramammary infusion