Codeine is a Dangerous Drug to Manage Post-Operative Pain for Children After Tonsillectomy

When you get your tonsils removed, of course, you're going to want a bowl of ice cream and a prescription of opiates. However, thanks to the U.S. Food and Drug Administration, children who have just had their tonsils and/or adenoids yanked aren't going to be able to indulge in the post-operative pain relief drug, codeine.

Yesterday, the U.S. FDA released a formalized warning that a subset of children with breathing difficulties from swollen tonsils are highly sensitive to the effects of codeine.

Hence, FDA is adding a strong warning to the drug label of codeine-containing products about the risk of the drug for post-operative pain management in children following tonsillectomy and/or adenoidectomy.

In addition to relieving pain, opioid analgesics like codeine suppress the respiratory control center of the brain. Combined with the obstructive sleep apnea already occurring in these kids, some of them are more hypersensitive than most for breathing suppression.

The FDA recognized this problem by reviewing adverse event reports recorded between 1969 and 2012. Codeine use in this scenario was associated with the death of ten children and an overdoses in three.

The reason for codeine's negative effectiveness in some kids and not others seems to stem from how the drug works relative to others in its class.

Most of the painkilling effects of codeine are due to some of it being converted to the strong opioid analgesic, morphine. While our bodies - particularly an enzyme in our livers called CYP2D6 - makes codeine active by replacing a part of the molecule to turn it into morphine, we usually think of drug metabolism as breaking drugs down. But in this case, drug metabolism produces a drug that's more active than the one taken.

Codeine is given at doses when this conversion is optimal for pain relief without adverse effects on breathing. However, a small percentage of people are born with a single-letter change in their DNA for this enzyme that causes the codeine-to-morphine reaction go faster. These people are called ultra-rapid metabolizers.

While having an ultra-rapid metabolizer may sound like a good thing, it unfortunately isn't. Then, when you take codeine, you convert much more of it to morphine than in most people, and if you're a kid with breathing problems from swollen tonsils and/or adenoids and are an ultra-rapid metabolizer, and are getting codeine for post-operative pain, the usual therapeutic dose is potentially lethal.