Quazolast is an orally active mast cell stabilising agent which was in development with Rhône-Poulenc Rorer. In preclinical trials Quazolast was evaluated for efficacy against acid independent (alcohol, HCl), or dependent (aspirin, indomethacin) gastric damage in rats. Quazolasts gastroprotective profile was compared to that of ranitidine. Quazolast, in direct contrast to ranitidine, protected the rat gastric mucosa from acid-independent, but not acid-dependent gastric damage. Quazolast lacked antisecretory activity in rats; however, it did heal acetic acid induced gastric ulcers in this species. In clinical trials Quazolast was superior to placebo in protecting against nasal congestion and nasal itchiness after ragweed nasal challenge.