III. Precautions

  1. AAP now approves Doxycycline for ANY age up to 21 day duration (esp. Tick Borne Illness)

IV. Formulations

  1. Capsule (Doxycycline Monohydrate)
    1. Strengths: 50,75,100,150 mg (generics available)
  2. Tablet (Doxycycline Monohydrate)
    1. Strengths: 50,75,100,150 mg (generics available)
  3. Tablet (Doxycycline Hyclate)
    1. Strengths: 20,50,75,100,150 mg (generics available)
  4. Doxycyline Hyclate Delayed-Release (Doryx MPC)
    1. Expensive ($10/pill) formulated to by-pass the esophagus for less side effects
    2. Alternatively, take the doxycyline with 8 oz water and food
    3. (2016) Presc Lett 23(11)

V. Dosing: Adults (weight >45 kg)

  1. Typical dose: 100 mg orally twice daily
  2. Low doses, such as 50 mg daily, are often as effective for Acne Vulgaris
  3. Avoid substituting low-dose Doxycycline (Periostat, Oracea) products for systemic infections
  4. May substitute other Doxycycline salts
    1. Doxycycline hyclate (Vibramycin, Doryx)
    2. Doxycycline monohydrate (Monodox)
    3. (2013) Presc Lett 20(5):26

VI. Pregnancy

  1. All Trimesters - Category D

VII. Adverse Effects

  1. Photosensitivity
    1. Use sun protection (e.g. Sunscreen)
  2. Pill Esophagitis
    1. Take with 8 ounces fluid
  3. Drug-Induced Tooth Staining
    1. Compared with Tetracycline, Doxcycyline is unlikely to cause tooth staining in children, even under age 8 years.
    2. Frequency: Uncommon to rare
  4. Abdominal Pain
  5. Diarrhea

VIII. Drug Interactions

  1. Doxycycline Decreases Absorption Of Other Substances
    1. Antacid
    2. Calcium Supplementation
  2. Doxycycline Level Decreased By Other Substance
    1. Barbiturate
    2. Carbamazepine
    3. Rifampin
    4. Phenytoin

IX. Pharmacokinetics

  1. Absorption: Not affected by food or milk intake (unlike Tetracycline)
  2. Peak Activity: >2.6 hours
  3. Half Life: 18-22 hours
  4. Primary Elimination: Renal (>40%)
  5. Other Elimination: Hepatic

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Related Studies

Cost: Medications

doxycycline (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
DOXYCYCLINE 25 MG/5 ML SUSP Generic $0.29 per ml
DOXYCYCLINE HYC DR 100 MG TAB Generic $8.83 each
DOXYCYCLINE HYCLATE 100 MG CAP Generic $0.49 each
DOXYCYCLINE HYCLATE 100 MG TAB Generic $0.63 each
DOXYCYCLINE HYCLATE 20 MG TAB Generic $0.36 each
DOXYCYCLINE HYCLATE 50 MG CAP Generic $0.59 each
DOXYCYCLINE IR-DR 40 MG CAP Generic $15.88 each
DOXYCYCLINE MONO 100 MG CAP Generic $0.42 each
DOXYCYCLINE MONO 100 MG TABLET Generic $0.50 each
DOXYCYCLINE MONO 150 MG TABLET Generic $5.36 each
DOXYCYCLINE MONO 50 MG CAP Generic $0.31 each
DOXYCYCLINE MONO 50 MG TABLET Generic $0.44 each