Not entirely. The original formulation results in an average 42% being absorbed. A pill that deviates from that formulation could be absorbed to a greater or lesser degree and would be like changing the dose. As long as you stay with the same formulation and tweak the dose based on bloodwork I'm sure things will stay consistant.
I agree xtane is top notch.
But even more important, if you take aromasin with a high fat meal, the effective dose is increased by 40%!
"Following oral administration of radiolabeled exemestane, 42% of radioactivity was absorbed from the gastrointestinal tract. Exemestane plasma levels increased by approximately 40% after a high-fat breakfast."