Oxycodone isn't a prodrug, unless you're talking about the tiny amount of oxymorphone it's metabolized into. But Oxycodone is active all on it's own, and makes up for the majority of it's analgesic properties. The Oxymorphone is responsible for only around 10% of it's effects.
My bad, I was basing that on a post I read here. Knew I shoulda double checked with wikipedia first.
