Pharm

Aminopenicillins

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Aminopenicillins, Ampicillin, Amoxicillin, Augmentin, Unasyn

  • See Also
  • Preparations
  • Amoxicillin and Ampicillin
  1. Ampicillin
    1. Child: 50-200 mg/kg/day IV divided qid
  2. Amoxicillin
    1. Maximum dose: Maximum dose: 3-4 grams/day
    2. Adult: 875 to 1000 mg orally twice daily
    3. Child
      1. Low dose: 45 mg/kg/day divided twice daily
      2. High dose: 90 mg/kg/day divided twice daily
  • Preparations
  • Added Beta-lactamase resistance
  1. Ampicillin Sulbactam (Unasyn)
    1. Adult: 1.5-3 grams IV every 6 hours
  2. Amoxicillin Clavulanate (Augmentin)
    1. Adult: 875 mg PO bid
    2. Child: 45 mg/kg/day divided PO bid
  • Mechanism
  1. Same as for Natural Penicillins
  2. Penetrates outer membrane of some Gram Negatives
  3. Clavulanic acid and sulbactam bind Beta-lactamases
  • Pharmacokinetics
  1. Keep Augmentin suspension refrigerated
  2. Clavulanate suspension breaks down at room Temperature
    1. Turns brown with breakdown
    2. Loses 90% of potency after 2 days at room Temperature
  • Pathophysiology
  • Bacterial Resistance Mechanisms Overcome
  1. Beta-lactamase Production
  2. Alteration of Penicillin binding protein
  • Adverse effects
  1. Similar to Natural Penicillins
  2. Maculopapular rash
    1. Onset 5-7 days after initiating medication
    2. Typically not IgE mediated (non-allergic)
      1. No immediate allergy (e.g. Urticaria), systemic symptoms or mucous membrane involvement
    3. Typically safe to use Amoxicillin in future if non-allergic rash alone
      1. Consider IgE Skin Testing if unclear rash etiology
    4. References
      1. Orman and Hayes in Herbert (2017) EM:Rap 17(7): 7-8
  3. Diarrhea (modifications can decrease stools to 12%)
    1. Dose exactly by kilogram for children
    2. Avoid food before dose
    3. Consider eating yogurt with each dose