Biotech Values

[Biowatch]

Short answer: Formulation. Slow release depends on "inert" ingredients that affect the rate of release of a simple molecule and how long it resides in the stomach or intestines before it gets into the blood stream, as well as how fast it gets eliminated before doing what it's supposed to.

Something as simple as the exterior coating makes most branded drugs easier to swallow than generics. If you wind up chewing it, then that can alter the absorption rate substantially.

This is a generic answer, pun intended, and others can weigh in with more substantive comments.