The first number is the active ingredient, in your case either
hydrocodone or
oxycodone, the second is, in your case,
acetaminophen since it's 500mg, hydro with
ibuprofen are always 200mg. No, Ibuprofen is not dangerous to the liver to the best of my recollection, acetaminophen can be toxic at the 4000mg/day dose, but it does take time for the damage to occur.
Maybe this chart is what you're looking for.
http://www.pharmer.org/imprints/narcotics
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