I believe it is nebulized theophilline, an older medicine that was taken orally long ago but is not prescribed much these days. As an oral medicine one has to check blood levels to be sure one didn’t have too much of it and had the right amount for it to be effective. The clinical trials suggested it may be able to reduce frequency & severity of exacerbations. Theophilline taken orally was effective for some patients as well. My docs are going to have me try Dupixent. They may have me try this one in the future.