Comparative antihistaminic and antiallergic activity of some antihistamnic drugs

Aim. To compare antihistaminic and antiallergic activity of antihistaminic drugs of the latest generation (ebastin, cetirisine, fexofenadine, loratadine) and antihistaminic drugs of the first generation (clemastin) in the same patients with pollenosis. Material and methods. Skin prick-titration with 10-dilution histamine and specific allergen, provocative nasal titration with 2-dilution histamine and allergen before and after a single intake of H-1-antagonists were made in 30 patients in stable clinical remission of pollenosis during maximal antihistamine activity of the above drugs. Results. Systemic administration of the known H-1-antagonists suppresses histamine sensitivity of both skin and nasal mucosa in the same degree. Drugs with more potent antihistaminic activity (fexofenadin and cetirisin) inhibited allergen-induced reactions more effectively. The order of the tested drugs by Suppression of allergen-provoked skin and nasal reactions (by lowering antiallergic activity) is the following: fexofenadin and cetirisin > ebastin and loratadin > clemastin. Conclusion. The above drugs of the latest generation seem to possess antiallergic activity not only due to antihistaminic effect but also due to other mechanisms. Different suppressive action of HI-antagonists reflects also individual sensitivity to different drugs. The factor of individual sensitivity of the patients to a pharmacological action of the drug may be crucial in the selection of the most effective medicine for each patient. This is confirmed by the data of individual sensitivity of the patient to antihistaminic and antiallergic action of H-1-antagonisis. The illustrated method may be helpful for individual selection of H-1-antagonists for treatment of patients with allergic diseases.