Codeine is a drug that reliefs pain and also treats cough. It is a component of many prescription and over-the-counter medicines. Codeine is metabolized in the liver into morphine with strong analgesic properties. However, its metabolizing enzyme, which is CYP2D6 has some genetic variability in the general population. Hence, people’s response to codeine varies in the general population. 

VARIABILITY IN RESPONSE TO THE USE OF CODEINE 

Some persons may not respond at all while others may over-respond to the drug. In a recent study, up to 2% of the general population has the ultra-fast metabolizing genetic variant of the CYP2D6 enzyme. Can you guess the total number of these ultra-fast metabolizers in a city with 10 million people? Patients who over-react to codeine experience unexpected respiratory depression. Some people, especially children, died after taking codeine. This group of persons who over-reacted to codeine has a genetic make-up that ultra-rapidly metabolizes codeine. Patients with a known history of wheezing and obstructive sleep apnea are more susceptible to the adverse events of codeine because they will be more sensitive to opioids. Patients with this risk factor and are also fast metabolizers of codeine are likely to have adverse drug reaction when they take codeine. The next question is, “where do we draw the line before we receive a prescription for a codeine-containing drug?” Likewise, what should a patient do when in a country where individuals buy drugs without a prescription? 

A LOGICAL ANSWER 

The answer is that people who are susceptible to the adverse effects of codeine, including parents of vulnerable kids, need to have a pharmacogenetics test to determine if they have the genetic variant of the CYP2D6 gene that is a fast or ultra-fast metabolizer. This simple test can spare the life of someone. No wonder adverse drug reaction is the 4th leading cause of death in the United States. In countries without appropriate record-keeping, the end of these persons can be attributed to something else, including unseen powers. Click to receive a FREE guide that can help you.