Lay summary
Codeine is commonly prescribed for pain relief. To become active, codeine needs to be converted into morphine by an enzyme called CYP2D6. Some people inherit high activity forms of this enzyme and are called “ultrarapid metabolisers”. When these people take codeine, they produce much higher levels of morphine than normal metabolisers. As an opioid, some people can misuse and become dependent or “addicted” to codeine. Our research suggests that this is a substantial, but under-recognised problem in New Zealand. We hypothesise that ultrarapid metabolisers are more susceptible to dependence.
This project will identify codeine-dependent individuals and collect saliva samples to enable assessment of inherited differences in the CYP2D6 gene. Successful completion would lead to a larger study to determine if codeine misuse/dependence potential is associated with inherited genes. Understanding which patient groups are at risk of codeine misuse would provide confidence that its use can be safe in the majority of people.