Codeinone is an isoquinolone alkaloid[1] found in the opium poppy.

[2] As an analgesic, it is one-third the potency of codeine.

It is an important intermediate in the production of hydrocodone–a painkiller about three-quarters the potency of morphine[citation needed]–as well as of oxycodone,[3] though the latter can also be synthesized from thebaine.

[4] Codeinone can be described as the methylether of morphinone: 3-methyl-morphinone.

Through renewed interest into possible anti-tumor activities of some of the opium alkaloids and derivatives, unrelated to their antinociceptive properties and habit-forming effects, the oxidation product of codeine has been found to induce cell death in three different human cancer cell lines in vitro.