Well from what I've read clenbuterol and ephedrine down regulates the alpha receptors and you're body gets used to the clen or ephedrine. The ketotifen supposedly up regulates those same receptors that the clen and ephedrine affect allowing your body to still react to lower doses of those two instead of building tolerance to them. I know for clen when you're off the cycle it helps, but I read mixed suggestions on using kitotifen after an eca stack which I'm taking at the moment.