Non-Sedating Antihistamine

Aka: Non-Sedating Antihistamine, Second Generation Antihistamine

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II. Indications

  1. Allergic Rhinitis

III. Mechanism

  1. Second Generation Antihistamine (Non-Sedating Antihistamine)

IV. 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.

V. 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)

VI. 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)

VII. 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

VIII. 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)

IX. 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]

X. 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

XI. 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

XII. 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

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Related Studies

Ontology: Histamine H1 Antagonists, Non-Sedating (C1136312)

Definition (MSH) A class of non-sedating drugs that bind to but do not activate histamine receptors (DRUG INVERSE AGONISM), thereby blocking the actions of histamine or histamine agonists. These antihistamines represent a heterogenous group of compounds with differing chemical structures, adverse effects, distribution, and metabolism. Compared to the early (first generation) antihistamines, these non-sedating antihistamines have greater receptor specificity, lower penetration of BLOOD-BRAIN BARRIER, and are less likely to cause drowsiness or psychomotor impairment.
Concepts Pharmacologic Substance (T121)
MSH D039563
SnomedCT 349956006, 372624008
French Anti-histaminiques H1 non sédatifs, Antihistaminiques de seconde génération, Anti-histaminiques de seconde génération, Antagonistes de l'histamine H1 non sédatifs, Antihistaminiques H1 non sédatifs
Swedish Histamin H1-blockerare, icke-sederande
English HISTAMINE H1 ANTAG NON SEDATING, HISTAMINE ANTAGONISTS H 001 NON SEDATING, antihistamines non sedating, non-sedating antihistamine, second generation antihistamine, antihistamines second generation, antihistamine non sedating, second generation antihistamines, Antihistamines, Second Generation, H1 Antihistamines, Non Sedating, H1 Antihistamines, Non-Sedating, Histamine H1 Antagonists, Non Sedating, Histamine H1 Antagonists, Non-Sedating, Non-Sedating H1 Antihistamines, Second Generation Antihistamines, Second Generation H1 Antagonists, Non-sedating antihistamine, Non-sedating antihistamine (product), Non-sedating antihistamine (substance), Histamine1 (H1) Blocking Agents, Mildly/Non-sedating
Czech histaminové H1-receptory - blokátory nesedativní, histamin H1 - antagonisté nesedativní
Finnish Väsyttämättömät antihistamiinit
German H1-Antagonisten der zweiten Generation, HISTAMIN ANTAGONISTS H 001 NICHT SEDIERENDE, Histamin-H1-Antagonisten, nicht sedierende
Russian GISTAMINA H1 ANTAGONISTY NESEDATIVNYE, ГИСТАМИНА H1 АНТАГОНИСТЫ НЕСЕДАТИВНЫЕ
Japanese 非鎮静性ヒスタミンH1拮抗剤, 非鎮静性H1抗ヒスタミンザイ, H1抗ヒスタミンザイ-非鎮静性, ヒスタミンH1拮抗剤-非鎮静性
Polish Antagoniści histaminy H1 bez działania uspokajającego, Antyhistaminiki H1 II generacji, Leki antyhistaminowe H1 II generacji, Leki przeciwhistaminowe H1 II generacji
Portuguese Antagonistas dos Receptores Histamínicos H1 não Sedativos, Antagonistas dos Receptores H1 da Histamina não Sedativos, Antagonistas dos Receptores H1 de Histamina não Sedativos
Spanish Antagonistas de los Receptores Histamínicos H1 no Sedantes, Antagonistas de los Receptores H1 de la Histamina no Sedantes, Antagonistas de los Receptores H1 de Histamina no Sedantes, antihistamínico no sedante (producto), antihistamínico no sedante (sustancia), antihistamínico no sedante
Italian Antagonisti dell'istamina H1, non sedativi
Derived from the NIH UMLS (Unified Medical Language System)

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