system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it necessary to have eaten food prior to taking some pills orally?

And how is it beneficial for these pills, but not others?
gpt
Two reasons: (1) sometimes pills irritate the stomach or bowel and eating food or drinking will protect them, and (2) sometimes food aids in the absorption of the active ingredient.

This is dependent on the pharmacokinetics and pharmacodynamics of each individual medication and is worked out either before or during phased clinical trials.