Codeine: Your DNA profile can determine whether it’s right for you
We don’t all respond the same way to the same medication. Codeine, which is prescribed for pain, is a good example. For codeine to relieve pain, it must first be metabolized in our bodies. In this process, the codeine is turned into morphine, which provides pain relief.
But because of their genetic make-up, some people metabolize codeine very fast, resulting in a morphine overdose, while some people metabolize it too slowly, so they don’t get enough morphine. Codeine is not appropriate for either the ultra‐rapid metabolizers or the poor metabolizers. Codeine is also not appropriate for children who have just had a tonsillectomy or adenoidectomy
A case is recorded of a 4-year-old boy who was discharged from hospital after a tonsillectomy with a codeine prescription. After just four doses at home he was rushed to the hospital without vital signs. The cause of death was found to be acute pneumonia caused by too much codeine and morphine in his body. This happened because his genetic make-up caused him to metabolize codeine very fast.
In another case, a breastfeeding mother was prescribed codeine with disastrous results. Because she was an ultra‐rapid metabolizer of codeine, the concentration of morphine in her breastmilk became extremely high, leading to the death of her 13-day-old infant.
Pharmacogenomic testing identifies variations within genes which may affect how a person’s body metabolizes various drugs, including codeine. These test results can help the doctor choose the safest and most effective drug and dose.