Actually it is +-20%, but close enough.
Here is where the problems arise. Let's say you are a diabetic and your blood sugar is controlled on X dose of generic A and generic A happens to be 15- 20% less bioavailable than the branded standard. The next month, you get the same dose of the same drug, but it is made by generic B, which happens to be 15-20% more bioavailable than the branded standard. You, the patient, crashes and the MD thinks that either you are not compliant or the generic drug sucks, when in reality the generic drug is perfectly fine.
