Singulair's great for its own thing -- it only suppresses one particular part of the immune system response -- the leukotrienes -- which leaves the rest of the inflammatory reaction open for everything else. This works great for people whose asthma doesn't comprise the entire inflammation pathway but rather just the leukotriene-histamine end of things.

They are, however, in their own right, immunosuppressants, if you want to get picky enough to cause Flovent an immunosuppressant.

The way I understand it is that they're one of those drugs that are very hit-and-miss, either you feel like a million bucks on it or you don't notice anything at all -- the singulair, that is. And just because Singulair didn't work for you doesn't mean that Accolate or something similar in the same category might not work anyway. It's one of those very, very arbitrary things.