Zafirlukast blocks the action of the cysteinyl leukotrienes on the CysLT1 receptors, thus reducing constriction of the airways, build-up of mucus in the lungs and inflammation of the breathing passages.
Zafirlukast is marketed by Astra-Zeneca 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, China and Turkey.
A letter was submitted to the FDA by Zeneca Pharmaceuticals on July 22, 1997, notifying them of a change in product labeling that includes the following potential reaction in patients undergoing a dosage reduction of oral steroids who are currently taking zafirlukast:
PRECAUTIONS-Eosinophilic Conditions: The reduction of the oral steroid dose, in some patients on ACCOLATE therapy, has been followed in rare cases by the occurrence of eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications, and/or neuropathy sometimes presenting as Churg Strauss Syndrome, a systemic eosinophilic vasculitis. Although a causal relationship with ACCOLATE has not been established, caution is required when oral steroid reduction is being considered.1