Antihistamines in rhinoconjunctivitis.
In allergic rhinoconjunctivitis, histamine is known to contribute predominantly to nasal itch, sneeze, rhinorrhea, conjunctival itch, and lacrimation and these symptoms benefit most from H1-antihistamine therapy. The discovery in the early 1980s of nonsedating H1-receptor antagonists contributed dramatically to the more widespread acceptance of this mode of therapy. This also led to the undertaking of well-designed clinical trials that have added significantly to our understanding of allergic rhinitis. Oral treatment modifies both nasal and ocular symptoms and provides effective control throughout a 24-h period with once- or twice-daily medication. The advent of topical H1-receptor antagonists offers a wider choice of treatments and provides equal or greater efficacy with lower systemic bioavailability. While having a major impact on rhinoconjunctivitis symptoms, H1-antihistamines do not fully modify disease since histamine is not the only contributor to symptom generation in allergic rhinoconjunctivitis. While the search for oral H1-antihistamines with more widespread "antiallergic" activity continues, the currently available medications modify predominantly histamine-regulated events despite in vitro evidence of greater potential. The development of these new medications may be the next significant advance in this mode of treatment.
University of Southampton, Southampton, England.
Peter
P
Howarth
D000818:Animals; D003233:Conjunctivitis, Allergic / Q000188:drug therapy* / Q000209:etiology; D006632:Histamine / Q000502:physiology; D006634:Histamine H1 Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D011968:Receptors, Histamine / Q000502:physiology; D012221:Rhinitis, Allergic, Perennial / Q000188:drug therapy* / Q000209:etiology; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy* / Q000209:etiology
D006634:Histamine H1 Antagonists; D011968:Receptors, Histamine; D006632:Histamine