There are many factors that go into that decision. First and foremost is the way to deliver the _active substance_. Can be immediate (pills are not the best fo

There are many factors that go into that decision. First and foremost is the way to deliver the _active substance_. Can be immediate (pills are not the best for immediate delivery), delayed (most common) or extended release (e.g. the AS gets released in doses over a period of time). Capsules IIRC can only deliver immediately but AS on capsules has faster absorption compared to pills. Cost is another factor: AFAIK pills are usually cheaper - although I don't work at the industry so don't quote on me on this. So it's the way you want to be delivered, characteristics of the AS, cost, etc. source: I have a 5-year degree (EU) in Pharmaceutical Sciences.