Here's the book answer:

Hydrocodone is a controlled substance according to 18-18-102 (5) - as best I can tell since that section goes on and on...

18-12-106. Prohibited use of weapons - definitions.
(1) A person commits a class 1 misdemeanor if:
(d) The person has in his or her possession a firearm while the person is under the influence of intoxicating liquor or of a controlled substance, as defined in section 18-18-102 (5).

Possession of a permit issued under section 18-12-105.1, as it existed prior to its repeal, or possession of a permit or a temporary emergency permit issued pursuant to part 2 of this article is no defense to a violation of this subsection (1).

O2