Zafirlukast is an oral leukotriene receptor antagonist (LTRA) for the maintenance treatment of asthma. Available as a tablet, it blocks the action of leukotriene C4 on its receptors, thus reducing constriction of the airways, build-up of mucus in the lungs and inflammation of the breathing passages.

Zafirlukast is marketed by AstraZeneca with the brand names Accolate, Accoleit, and Vanticon. It was the first LTRA to be marketed in the USA and is now approved in over 60 countries, including the UK, Japan, Italy, Spain, Canada, Brazil and China.