Codeine is a prodrug converted to morphine by the CYP2D6 enzyme. The amount produced varies dramatically by genotype: poor metabolizers get little analgesia, while ultra-rapid metabolizers convert codeine into very high morphine levels rapidly, with risk of life-threatening or fatal respiratory depression. The FDA has issued strict boxed warnings: (1) contraindicated in any child under 12 years for any indication; (2) contraindicated in any child under 18 years for postoperative pain after tonsillectomy or adenoidectomy because deaths have been reported even with usual doses; (3) contraindicated in breastfeeding women because morphine passes into breast milk and has caused infant deaths from respiratory arrest; (4) caution in adolescents 12 to 17 with obesity, sleep apnea, or severe lung disease because of overlapping respiratory risk; (5) tramadol carries an essentially identical pediatric and breastfeeding warning. Safer alternatives in these populations: acetaminophen, ibuprofen (over 6 months), or non-codeine opioids such as hydrocodone or oxycodone for short-term severe pain when needed. Halving doses, refusing only one of the two prescriptions, or accepting the prescription as written are unsafe. The nurse contacts the prescriber to communicate the boxed warning and request a change.
For study reference only. Always follow current clinical guidelines and your institution’s protocols.