H1-Histamine Receptor Antagonists

Indications

Treatment of Histamine-Mediated Allergic Diseases


Agents

First Generation Antihistamines (H1-Histamine Receptor Antagonists)

Ethanolamines

  • Bromazine
  • Carbinoxamine
  • Clemastine
  • Dimenhydrinate
  • Diphenhydramine (Benadryl) (see Diphenhydramine, [[Diphenhydramine]])
  • Doxylamine
  • Orphenadrine

Ethylenediamines

  • Antazoline
  • Mepyramine (Pyrilamine)
  • Tripelennamine

Alkylamines

  • Brompheniramine
  • Chlorpheniramine (Chlorphenamine)
  • Dexbrompheniramine
  • Dexchlorpheniramine
  • Dimetindene
  • Pheniramine
  • Triprolidine

Piperazines

  • Chlorcyclizine
  • Cyclizine
  • Hydroxyzine (Atarax, Vistaril) (see Hydroxyzine, [[Hydroxyzine]])
  • Meclizine (Bonine, Bonamine, Antivert, Postafen, Sea Legs, Dramamine) (see Meclizine, [[Meclizine]])

Tricyclics/Tetracyclics

  • Alimemazine (Trimeprazine)
  • Azatadine
  • Cyproheptadine
  • Ketotifen
  • Promethazine (Phenergan) (see Promethazine, [[Promethazine]])

Second Generation Antihistamines (H1-Histamine Receptor Antagonists)

Systemic

  • Acrivastine
  • Astemizole (Hismanal) (see Astemizole, [[Astemizole]]): withdrawn from US market
  • Bepotastine
  • Bilastine
  • Cetirizine (Zyrtec) (see Cetirizine, [[Cetirizine]])
  • Ebastine
  • Ketotifen
  • Loratidine (Claritin) (see Loratidine, [[Loratidine]])
  • Mizolastine
  • Quifenadine
  • Rupatadine
  • Terfenadine (Seldane) (see Terfenadine, [[Terfenadine]]): withdrawn from US market

Topical

  • Azelastine
  • Levocabastine
  • Olopatadine

Third Generation Antihistamines (H1-Histamine Receptor Antagonists)

  • Desloratadine (Clarinex) (see Desloratadine, [[Desloratadine]])
  • Fexofenadine (Allegra, Axodin) (see Fexofenadine, [[Fexofenadine]])
  • Levocetirizine (Xyzal) (see Levocetirizine, [[Levocetirizine]])

Pharmacology

  • H1-Histamine Receptor Antagonism: antihistamine effect

Contraindications

  • xxx

Adverse Effects (First-Generation Agents)

Cardiovascular Adverse Effects

  • Hypotension (see Hypotension, [[Hypotension]])
  • Palpitations
  • QT Prolongation with Variable Association with Torsade (see Torsade, [[Torsade]])
    • Agents
      • Diphenhydramine (Benadryl) (see Diphenhydramine, [[Diphenhydramine]]): QT prolongation with definite association with torsade
      • Hydroxyzine (Atarax, Vistaril) (see Hydroxyzine, [[Hydroxyzine]]): QT prolongation without definite association with torsade
    • Physiology: class effect

Gastrointestinal Adverse Effects

  • Constipation
  • Diarrhea
  • Dry Mouth
  • Nausea and Vomiting

Neurologic Adverse Effects

  • Blurred Vision
  • Dizziness
  • Headache
  • Hallucination/Psychosis
  • Insomnia
  • Tinnitus
  • Sedation: more common with first-generation antihistamines (due to relative lack of selectivity for the H1-receptor and ability to cross the blood-brain barrier)

Other Adverse Effects

  • Urinary Retention

Adverse Effects (Second-Generation Agents)

Cardiovascular Adverse Effects

  • QT Prolongation with Variable Association with Torsade (see Torsade, [[Torsade]])
    • Agents
      • Astemizole (Hismanal) (see Astemizole, [[Astemizole]]): QT prolongation with definite association with torsade
      • Ebastine: QT prolongation without definite association with torsade
      • Loratidine (Claritin) (see Loratidine, [[Loratidine]]): QT prolongation with definite association with torsade
      • Mizolastine: QT prolongation without definite association with torsade
      • Terfenadine (Seldane) (see Terfenadine, [[Terfenadine]]): QT prolongation with definite association with torsade
    • Physiology: class effect

Gastrointestinal Adverse Effects

  • Dry Mouth
  • Nausea

Neurologic Aderse Effects

  • Fatigue
  • Headache
  • Sedation

References

  • xxx