• See Also
  1. Tetracyclines
  2. Doxycycline
  • Indications
  1. Skin disorders
    1. Methicillin-Resistant Staphylococcus Aureus (MRSA) Skin Infections
    2. Acne Vulgaris
    3. Acne Rosacea
  2. Gastrointestinal disorders
    1. Helicobacter Pylori (part of quadruple therapy protocol)
  3. Tick-borne illness
    1. Lyme Disease
    2. Human Granulocytic Anaplasmosis (Human Granulocytic Ehrlichiosis)
    3. Rocky Mountain Spotted Fever
  4. Miscellaneous disorders
    1. Community Acquired Pneumonia
    2. Malaria Prophylaxis
  5. Sexually Transmitted Disease
    1. Chlamydia Trachomatis
    2. Lymphogranuloma venereum
  • Contraindications
  1. Pregnancy
    1. Pregnancy category D
  2. Children under age 8 years old
    1. AAP now approves Doxycycline for ANY age up to 21 day duration
    2. Unlike Tetracycline, Doxycycline is unlikely to cause visible tooth staining
    3. For severe infections (e.g. Lyme Disease, Rocky Mountain Spotted Fever), Doxycycline is a first-line agent
  • Mechanism
  1. See Tetracycline
  2. Tetracyclines are bacteriostatic Protein synthesis inhibitors, binding the 30S ribosomal subunit of susceptible Bacteria
  3. Prevents elongated peptide chains from forming from Amino Acid residues
    1. Inhibits Amino Acid-linked tRNA from binding at the Ribosomal A Site
  • Dosing
  1. Acne Vulgaris
    1. Take 1 gram divided two to four times orally daily
  • Pharmacokinetics
  1. Does not penetrate CSF
  2. Concentrated by the liver via enterohepatic circulation
  3. Excreted in urine and stool
  • Precautions
  1. Use Sunscreen with these agents due to Drug-induced Photosensitivity
  2. Pill Esophagitis
    1. Take with a full glass of water
  • Adverse Effects
  1. Photosensitivity
  2. Interferes with OCP action
  3. Tooth Discoloration (Children under age 8 years)
    1. Tooth enamel hypoplasia
    2. Rare with Doxycycline
  4. Pseudotumor Cerebri
    1. Rare Tetracycline class effect
  • Safety
  1. Pregnancy Category D
  2. Unknown safety in Lactation
  • Drug Interactions
  1. Food
    1. Milk and Calcium-rich food decrease absorption
    2. Take 1 hour before or 2 hours after a meal
    3. Take with a full glass of water (risk of Pill Esophagitis)
  2. Warfarin
    1. Increases INR
  • Resources
  1. Tetracycline (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2854d3b7-f874-4c67-8014-adda9639f515
  • References
  1. (2019) Tarascon Pharmacopeia, accessed 3/31/2019
  2. LoVecchio (2019) Crit Dec Emerg Med 33(3): 28