COMPARISON OF AZELASTINE AND CHLORPHENIRAMINE IN THE TREATMENT OF MASTOCYTOSIS

Background: Azelastine, a novel antiallergic medication, was compared with chlorpheniramine maleate for efficacy and safety in the treatment of systemic mastocytosis. Methods: Fifteen subjects with mastocytosis participated in a double-blind, randomized, three-period, crossover t rial, which compared an azelastine regimen of 4 mg or 8 mg every 12 ho urs with a chlorpheniramine regimen of 12 mg every 12 hours. Response to therapy was assessed by daily symptom scores, extinction dilution s kin tests, plasma histamine levels, and global evaluations. Results: S ubjects' mean wheal area responses provoked by histamine or morphine s ulfate were significantly lowered by azelastine when compared with chl orpheniramine. Plasma histamine levels in subjects receiving azelastin e or chlorpheniramine were not significantly different. There were no significant differences between azelastine and chlorpheniramine in ind ividual symptom scores or global evaluations except that azelastine at both doses significantly relieved pruritus and at 4 mg significantly relieved abdominal pain and that chlorpheniramine was associated with less fatigue in comparison to azelastine at 8 mg. Conclusions: It thus appears that azelastine is superior to chlorpheniramine in suppressin g skin responses to histamine and morphine sulfate and in suppressing pruritus in patients with mastocytosis. However, when all parameters a re considered, neither drug is clearly superior for the treatment of p atients with mastocytosis.