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Cetirizine

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Cetirizine, Zyrtec, Levocetirizine, Xyzal

  • See Also
  1. Second Generation Antihistamine
  2. Antihistamine
  3. Allergic Rhinitis
  • Indications
  1. Allergic Rhinitis
    1. More rapid onset than other Non-Sedating Antihistamines (1 hour instead of 3 hours)
      1. Allows as needed dosing (such as for acute reactions, as allergists frequently used)
  • Mechanism
  1. Second Generation Antihistamine
  2. Cetirizine and Levocetirizine are analogs of the Sedating AntihistamineHydroxyzine
    1. Most sedating of the Non-Sedating Antihistamines (Second Generation Antihistamines)
  • Dosing
  • Cetirizine (Zyrtec)
  1. FDA approved for perennial allergies in age >=6 months (seasonal allergies in age >=2 years)
  2. Allergists frequently prescribe Cetirizine in Allergic Reactions at higher dose and twice daily (off label use)
  3. Available OTC in U.S. since 2007
    1. Tablets or chewables: 5-10 mg
    2. Syrup 5 mg/5 ml
  4. Adult Dose (includes ages 6-11): 5 to 10 mg orally daily
  5. Child Dose (ages 2-5 years): 2.5 mg orally daily to twice daily
  6. Infant Dose (ages 6 months to 2 years): 2.5 mg orally daily
  7. Decrease dose in renal or hepatic Impairment
  • Dosing
  • Levocetirizine (Xyzal)
  1. Active isomer of Cetirizine (Zyrtec), hence dosing is 50% of Cetirizine
  2. FDA approved for age >=6 months
  3. Adult Dose (ages 12 and over): 5 mg orally daily
  4. Child Dose (ages 6-11 years): 2.5 mg orally daily
  • Safety
  1. Contraindicated in Lactation (Cetirizine and Levocetirizine)
  2. Pregnancy Class B agents (Cetirizine and Levocetirizine)
  • Adverse Effects
  1. See Antihistamine
  2. Drowsiness
    1. Although labeled as non-sedating, these Antihistamines may still cause sedation (esp. Cetirizine)
    2. May be sedating even at normally recommended doses (Hydroxyzine analog); reported by 10% of patients
  • References
  1. Howarth (1999) J Allergy Clin Immunol 104:927 [PubMed]
  2. Walsh (2001) Drugs 61:207 [PubMed]
  3. (2001) Med Lett Drugs Ther 43(1103):35