The influence of cimetidine and ranitidine on basophil histamine release and bronchial reactivity in asthmatic patients.

Anti-IgE induced histamine release from isolated basophils after Cimetidine and Ranitidine administration was evaluated in 22 patients with atopic bronchial asthma. The histamine provocation test after Ranitidine treatment in 10 patients with atopic bronchial asthma and 10 patients with peptic ulcer was also performed. Investigations in vitro revealed that Cimetidine and Ranitidine in low concentrations had an inhibitory effect whereas in concentrations of over 10(-6) M and 10(-4) M, respectively, they enhanced histamine release. Investigations in vivo after administration of Ranitidine showed that it does not cause marked changes in the bronchial reactivity in patients with bronchial asthma and any change in patients with peptic ulcer. These preliminary studies seem to suggest that in patients with atopic bronchial asthma and concomitant peptic ulcer Ranitidine is preferable to Cimetidine in the treatment of digestive tract disorders.