Hello Sammi and Welcome! I'm glad that you found us and hope that you'll be active in our community.
You've asked a good question. This is a chemistry question - and chemistry is not my strong suit. However I've done a lot of research and reading in UDT (Urinary Drug Test) and though I may not understand it totally I get the basis.
Metabolites are really what these UDT are measuring. Oxycodone produces different metabolites and that of Hydrocodone. If your PMP uses the quick inexpensive UDT which basically says positive or negative for opiates you should "pass" that UDT.
If your PMP utilizes the more sophisticated, expensive and 99% accurate UDT this will be close. I can't say for positive if the Hydrocodone will show up or not. Research says that Hydrocodone remains traceable in our urine approximately 72 to 96 hours after last consumption. That's the norm.
Hope that helps. Please try to take only what your PMP prescribes. You risk losing PM - and that would be tragic!