Codeine and fluoxetine

Codeine and fluoxetine. Codeine is metabolized to morphine by cytochrome P450 2D6 (CYP2D6), which explains its analgesic activity. Fluoxetine is a CYP2D6 inhibitor that results in a defect in the metabolism of codeine to morphine and, consequently, a decrease in its analgesic activity. When co-prescribing codeine and fluoxetine, the dispensing pharmacist should contact the prescriber to suggest substituting morphine for codeine, at a low dose and for a short duration. (c) 2023 Elsevier Masson SAS. All rights reserved