IV codeine potency relative to morphine is equivalent to how many mg of morphine?

IV codeine potency relative to morphine is equivalent to how many mg of morphine?

• A. 60 mg morphine
• B. 20 mg morphine
• C. 10 mg morphine
• D. 5 mg morphine

Answer: (C)

In equianalgesic dosing, we compare opioids by how much morphine would give the same pain relief. IV codeine is much less potent than IV morphine because codeine’s analgesia mainly comes from its metabolite morphine, and the parent drug itself has relatively weak activity. This makes IV codeine roughly one-tenth as potent as morphine. So, the morphine dose that would produce the same analgesic effect as a given dose of IV codeine is about tenfold higher. Clinically, this translates to about 10 mg of morphine being equivalent in effect to IV codeine. The other numbers would imply potencies that don’t fit this established 1:10 relationship.

In equianalgesic dosing, we compare opioids by how much morphine would give the same pain relief. IV codeine is much less potent than IV morphine because codeine’s analgesia mainly comes from its metabolite morphine, and the parent drug itself has relatively weak activity. This makes IV codeine roughly one-tenth as potent as morphine. So, the morphine dose that would produce the same analgesic effect as a given dose of IV codeine is about tenfold higher. Clinically, this translates to about 10 mg of morphine being equivalent in effect to IV codeine. The other numbers would imply potencies that don’t fit this established 1:10 relationship.