Ketotifen
Not w/ IBE, but have used their stuff, including both products mentioned for awhile. Ketotifen clears receptors, not just for clen & albuterol (which I agree is better in light of recent animal research on clen), but also all beta agonists such a synepherine, ephedra (& ine) etc...
I'd start it about 2nd night (clen saturation of receptors starts after 2 days- think that's the soonest of all such substances) of anything & take .5 - 2 eod @ night. It will also tend to make one drowsy & help you sleep.
Just for refs, I'm a former colllege & pro athlete & supplement company owner & now one of my state's top medical malpractice trial attorneys. Not a chemist, but this stuff has been a long term hobby &, at times, a job. Hope this helps.