Comparison of the therapeutic efficacy of cromolyn sodium with that of combined chlorpheniramine and cimetidine in systemic mastocytosis. Results of a double-blind clinical trial.

Both antihistamines and cromolyn sodium have been suggested for the treatment of systemic mastocytosis. To determine if one drug regimen was superior to the other, eight patients with systemic mastocytosis were admitted to a double-blind, double-crossover study in which the therapeutic efficacy of cromolyn sodium was compared with that of a combination of chlorpheniramine and cimetidine. Response to therapy was assessed by the patients using symptom scores and by the attending physicians during clinic examinations in addition to sequential plasma and urinary histamine determinations. In the six patients who completed the trial, the patient symptom scores and the physician evaluations indicated that there was no advantage of one drug regimen over the other. Plasma and urinary histamine levels, markedly elevated in most of the patients, were not consistently altered by administration of either cromolyn sodium or the combined antihistamines. Thus, cromolyn sodium and the combined antihistamines were indistinguishable when used for the symptomatic treatment of systemic mastocytosis, and neither regimen altered systemic histamine levels.