Antihistamines: topical vs oral administration

Area of Science:

• Immunology
• Pharmacology
• Otorhinolaryngology

Background:

• Allergic rhinitis pathogenesis involves multiple inflammatory mediators beyond histamine.
• Second-generation antihistamines, despite targeting only histamine, show significant clinical efficacy.
• Research investigates additional pharmacological activities of antihistamines.

Purpose of the Study:

• To explore the non-histaminergic anti-inflammatory effects of second-generation antihistamines.
• To compare the efficacy and safety of topical versus oral antihistamine administration.
• To evaluate the impact of antihistamines on intercellular cell adhesion molecule-1 (ICAM-1) expression.

Main Methods:

• In vitro studies assessing mediator release and ICAM-1 expression.
• In vivo studies evaluating nasal symptoms and inflammatory cell influx.
• Clinical trials comparing topical (levocabastine, azelastine) and oral (terfenadine, cetirizine) antihistamines, and intranasal azelastine versus beclomethasone dipropionate.

Main Results:

• High concentrations of antihistamines inhibit inflammatory mediator release and reduce ICAM-1 expression.
• Oral and intranasal antihistamines reduce nasal symptoms and inflammatory cell influx.
• Topical levocabastine and azelastine demonstrated superior or comparable efficacy to oral terfenadine and beclomethasone, with improved safety profiles.

Conclusions:

• Second-generation antihistamines possess additional anti-inflammatory properties.
• Topical antihistamine administration offers enhanced efficacy and safety for allergic rhinitis management.
• Targeted delivery to the affected organ is a logical approach for antihistamine therapy.