Pharm

Macrolide

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Macrolide, Erythromycin

  • Mechanism of action
  1. Reversibly binds 50S ribosomal subunit
  2. Inhibits Protein synthesis
  • Bacterial resistance mechanisms
  1. Impermeability of Bacterial outer membranes
    1. Especially Gram Negative Organisms
  2. Production of enzymes that alter ribosomal targets
  • Adverse Effects
  1. Gastrointestinal upset
  2. Nausea
  3. Cholestatic Jaundice
  4. Multiple Drug Interactions
  • Complications
  1. Candida Vaginitis infection
  2. Gram Negative Folliculitis
  • Pharmacokinetics
  1. Half life: 1.5 hours
  • Drug Interactions
  1. Interactions may also occur with extended spectrum
    1. Clarithromycin
    2. Telithromycin
    3. Less likely to occur with Azithromycin
  2. QT Prolongation (Erythromycin with an agent below)
    1. Calcium Channel Blockers increase Erythromycin level
      1. Verapamil
      2. Diltiazem
    2. Other potent CYP3A4 inhibitors
      1. Ketoconazole
      2. Itraconazole
      3. Nefazodone
      4. Protease Inhibitors
  3. References
    1. Ray (2004) N Engl J Med 351:1089-96 [PubMed]
  • Oral Preparations (Take with food to reduce GI Upset)
  1. Erythromycin base 1000 mg/day PO divided bid-qid
  2. Erythromycin ethyl succinate (EES)
    1. Adult: 400 mg PO qid
    2. Child: 30-50 mg/kg/day PO divided qid
  • Parenteral Preparation
  • Erythromycin lactobionate
  1. Dose: 15 to 20 mg/kg/day IV divided every 6 hours
  2. Maximum: 4 grams
  • Activity Spectrum
  1. Major indications for Erythromycin
    1. Chlamydia pneumoniae
    2. Chlamydia trachomatis
      1. Pneumoniae or Conjunctivitis
      2. Pelvic infection in pregnancy
    3. Legionella pneumophila
    4. Mycoplasma pneumoniae
    5. Bordetella pertussis
    6. Corynebacterium diphtheriae
    7. Campylobacter jejuni
  2. Other organisms covered
    1. Ureaplasma urealyticum
    2. Treponema pallidum (Syphilis)
    3. Staphylococcus
    4. Streptococcus
    5. Bacillus anthracis
    6. Clostridium species