Fatty foods cheat the time mechanism of Opana (SR discontinued though?) allowing it to
peak faster and yielding a higher Cmax, and so potency , although average person, even user, could be playing with fire; the effects somewhat unpredictable. Another example being gabapentin, slightly improved absorption with food; though more important to space out doses (hence The, encarbinel(sic?) version to get around these issues, and Lyrica)
Mostly, though, and empty stomach, and water, or say sip of coffee w/ half, other 10-15 minutes later because of gastric emptying
reallly almost too broad a list, though say 10 or 15 relevant or common examples could do for something in a single post
Reasearch, my pals