(a) In this chapter:
(1) "Dextromethorphan" means any compound, mixture, or preparation containing any detectable amount of that substance, including its salts, optical isomers, and salts of optical isomers.
(2) "Sale" includes a conveyance, exchange, barter, or trade.
(b) A term that is used in this chapter but is not defined by Subsection (a) has the meaning assigned by Section 481.002 if the term is defined in that section.