II. 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

III. 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

IV. Mechanism

  1. Same as for Natural Penicillins
  2. Amino Acid side group
    1. Hydrophilic, and allows penetration via pores in Gram Negative Bacterial outer membrane
  3. Clavulanic acid and sulbactam bind Beta-Lactamases and block Penicillinases

V. 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

VI. Pathophysiology: Bacterial Resistance Mechanisms Overcome

  1. Beta-Lactamase Production
  2. Alteration of Penicillin binding Protein

VIII. 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

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