United Kingdom. The manufacturer of the leukotriene antagonist, montelukast (Singulair: Merck), has revised the product information to include a caution concerning eosinophilic conditions, sometimes consistent with Churg- Strauss syndrome associated with the use of this product. Montelukast is indicated for the treatment of asthma.

The sections on Precautions and Adverse Reactions will contain the following text:

“In rare cases, patients on therapy with montelukast (Singulair) may present with systemic eosinophilia, sometimes presenting with clinical features of vasculitis consistent with Churg-Strauss syndrome, a condition which is often treated with systemic corticosteroid therapy. These events usually, but not always, have been associated with the reduction of oral corticosteroid therapy. Physicians should be alert to eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications and/or neuropathy presenting in their patients. A causal association between montelukast and these underlying conditions has not been established.”

[See also Pharmaceuticals Newsletter Nos. 9 & 10, September & October 1998 and Nos. 5 & 6, May & June 1998]

Reference: “Dear Healthcare Professional” letter, Merck & Co., December 1998.
[http://www.fda.gov/medwatch/safety/1998/singul.htm]