Codeine

alkaloid · nervous · respiratory · digestive · Oral

Codeine, an alkaloid. Methylated morphine prodrug — analgesic effect requires hepatic CYP2D6 demethylation to morphine, the active µ-opioid… Oral half-life 3 h.

Methylated morphine prodrug — analgesic effect requires hepatic CYP2D6 demethylation to morphine, the active µ-opioid receptor agonist (~10% of dose). CYP2D6 ultrarapid metabolizers risk respiratory depression; poor metabolizers get little analgesia.

Pharmacokinetics

• Oral — t½ 3 h · F 50% · ka 1.624 h⁻¹ · Vd 245 L

Sources: PMID:8227477