Suppressive effect of loratadine on allergen-induced histamine release in the nose.
It has been speculated whether the recently developed non-sedating antihistamines may possess other properties than merely being antagonists at the H1-receptors. To investigate this suggestion 12 patients with strictly seasonal allergic rhinitis participated in a double-blind placebo controlled randomized cross-over study outside the pollen season. At steady state levels of 10 mg loratadine, a new non-sedating antihistamine, the patients were challenged with methacholine. This was followed by a nasal challenge with increasing doses of allergen. 24 h later the patients were rechallenged nasally with the same methacholine dose as the day before. The volume of the methacholine-induced nasal secretion was measured and the response to allergen was determined by scoring technique. In returned nasal lavage fluid the levels of histamine and TAME-esterase activity were measured. It was found that loratadine significantly reduced the immediate allergic nasal symptoms compared with placebo (P less than 0.01). Loratadine also reduced the allergen-induced release of histamine into the nasal cavity after the strongest allergen dose, from 9.6 +/- 1.5 (mean +/- SEM) to 6.4 +/- 1.4 ng/ml (P less than 0.05). A similar decrease in the TAME-esterase activity after treatment with loratadine was observed. The TAME-esterase activity decreased from 11.6 *10(3) +/- 2.47 *10(3) to 5.60 *10(3) +/- 1.45 *10(3) CMP (P less than 0.05). There were no significant changes between the active and placebo treatments regarding the methacholine-induced secretory response. This was true for the initial methacholine challenge as well as the secretory response 24 h later.(ABSTRACT TRUNCATED AT 250 WORDS)
Andersson
M
M
Department of Oto-rhino-laryngology, University Hospital, Lund, Sweden.
Nolte
H
H
Baumgarten
C
C
Pipkorn
U
U
D000293:Adolescent; D000328:Adult; D000485:Allergens; D003533:Cyproheptadine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D006634:Histamine H1 Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D006636:Histamine Release / Q000187:drug effects*; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000188:drug therapy / Q000276:immunology; D017336:Loratadine; D008297:Male; D009299:Nasal Provocation Tests; D009666:Nose / Q000187:drug effects* / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy / Q000276:immunology*
D000485:Allergens; D006634:Histamine H1 Antagonists; D003533:Cyproheptadine; D017336:Loratadine