Tiacrilast (also known as Ro 22-3747) is a quinazolinyl-propenoic acid derivative patented by Hoffmann-La Roche, Inc. as an antihypertensive useful for anaphylaxis management. Tiacrilast acts as a potent mast cell degranulation inhibitor in vitro and inhibits of antigen-induced histamine release from passively sensitized rat peritoneal cells in vitro. In preclinical models, Tiacrilast shows marked activity in rat passive cutaneous anaphylaxis assay, rat anaphylactic bronchospasm assay. In vitro studies have confirmed that the mechanism of action of Tiacrilast in the in vivo models is through allergic mediator release inhibition. Clinical evaluations of Tiacrilast in patients with ragweed sensitive allergic asthma, Tiacrilast demonstrates significant inhibitory activity relative to placebo in reducing acute airway responses to inhaled pollen extracts