Pharm

Non-Sedating Antihistamine

search

Non-Sedating Antihistamine, Second Generation Antihistamine

  • See Also
  1. Antihistamine
  2. Loratadine
  3. Cetirizine
  4. Fexofenadine
  • Indications
  1. Allergic Rhinitis
  • Mechanism
  1. Second Generation Antihistamine (Non-Sedating Antihistamine)
  • Background
  1. Original second generation agents astemizole (Hismanal) and terfenadine (Seldane) were discontinued for adverse effects
  2. Most second generation agents are now available OTC in the U.S.
  • Medications
  • Advantages and Disadvantages
  1. Fexofenadine (Allegra)
    1. Least sedating, even in higher doses
  2. Loratadine (Claritin)
    1. Sedating at higher doses
    2. Less potent than Allegra and Zyrtec
  3. Cetirizine (Zyrtec) and Levocetirizine (Xyzal)
    1. May be sedating even at normally recommended doses (Hydroxyzine analog); reported by 10% of patients
    2. More rapid onset than other Non-Sedating Antihistamines (1 hour instead of 3 hours)
      1. Only significant if Antihistamine is taken as needed (instead of daily)
  • Medications
  • Oral by Age Restrictions
  1. Age 6 months and older
    1. Cetirizine (Zyrtec, Pregnancy category B)
    2. Desloratadine (Clarinex, Pregnancy category C, perennial allergies)
    3. Levocetirizine (Xyzal, Pregnancy category B, perennial allergies)
  2. Age 2 years and older
    1. Loratadine (Claritin, Pregnancy category B)
    2. Desloratadine (Clarinex, Pregnancy category C, seasonal allergies)
    3. Levocetirizine (Xyzal, Pregnancy category B, seasonal allergies)
  3. Age 6 years and older
    1. Fexofenadine (Allegra, Pregnancy category C)
  • Medications
  • Oral
  1. Fexofenadine (Allegra, OTC, Tabs 30-60-180 mg, Dissolving 30 mg, Suspension 30 mg/5ml)
    1. Adult Dose (ages 12 and over): 60 mg orally twice daily or 180 mg orally daily
    2. Child Dose (ages 6-11 years): 30 mg orally twice daily
    3. Low sedation and highly effective
  2. Loratadine (Claritin, OTC, tabs 10 mg, Dissolving 5-10 mg, Syrup 1mg/ml)
    1. Adult Dose (ages 6 and over): 10 mg orally daily
    2. Child Dose (ages 2-5 years): 5 mg orally daily
  3. Cetirizine (Zyrtec, OTC, Tabs or Chewables 5-10 mg, Syrup 5 mg/5 ml)
    1. Adult Dose (includes ages 6-11): 5 or 10 mg orally daily
    2. Child Dose (ages 2-5 years): 2.5 mg orally daily to twice daily
    3. Infant Dose (ages 6 months to 2 years): 2.5 mg orally daily
  4. Levocetirizine (Xyzal, OTC, Scored Tabs 5 mg, solution 2.5 mg/5ml)
    1. Active isomer of Cetirizine (Zyrtec)
    2. Adult Dose (ages 12 and over): 5 mg orally daily
    3. Child Dose (ages 6-11 years): 2.5 mg orally daily
  5. Desloratadine (Clarinex, prescription only, tabs 5 mg, Dissolving 2.5-5 mg, Syrup 0.5 mg/ml)
    1. Adult Dose (ages 12 and over): 5 orally daily
    2. Child Dose (ages 6-11 years): 2.5 mg orally daily to twice daily
    3. Preschool Dose (ages 12 months to 5 years): 1.25 mg orally daily
    4. Infant Dose (ages 6-12 months): 1 mg orally daily
  • Preparations
  • Nasal
  1. Azelastine (Astelin) 1-2 sprays per nostril twice daily (ages 5 and over)
  2. Olopatadine (Patanol) 2 sprays per nostril twice daily (ages 12 and over)
  • Safety
  1. Contraindicated in Lactation
  2. Pregnancy Class B agents (other agents are Category C)
    1. Cetirizine (Zyrtec)
    2. Loratadine (Claritin)
    3. Levocetirizine (Xyzal)
  3. Pregnancy Class C agents
    1. Fexofenadine (Allegra)
      1. Appears as safe in pregnancy as other Non-Sedating Antihistamines that are category B (Cetirizine, Loratadine)
      2. Andersson (2020) JAMA Pediatr 174(8): e201316 [PubMed]
  • Adverse Effects
  1. See Antihistamine
  2. Drowsiness
    1. Although labeled as non-sedating, these Antihistamines may still cause sedation (esp. Cetirizine)
    2. Sedation may be least likely with Loratadine (Claritin) at lower doses, and Fexofenadine (Allegra) at any dose
  • Drug Interactions
  1. Fexofenadine
    1. Absorption decreased by orange juice, Grapefruit juice, apple juice (separate by at least 4 hours)
  2. Historical Only: Astemizole (Hismanal) and Terfenadine (Seldane)
    1. QTc Prolongation
    2. Contraindicated with Erythromycin, Ketoconazole
    3. Resulted in fatal Arrhythmias in multiple cases
  • 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