I'm glad that you found the information helpful. CYP2D6 testing is available through doctors, genetics clinics, and companies like mine (DNA Direct).
wow, what a thorough answer, that really helps me a lot. i'll certainly talk to my doctor about it, since he didn't bring it up, and i appreciate that NPR and you gave me this great information. I certainly don't want higher than expected levels of morphine in my blood or give it to my nursing infant. i'll take small amounts, just enough for the pain.
The FDA issued an alert to breastfeeding mothers on August 17, 2007, and can be found on the FDA’s website. The statement recommends that when prescribing codeine to nursing mothers, physicians should choose the lowest effective dose for the shortest period of time and should closely monitor mother-infant pairs.
Codeine is one of many medications that is processed by a gene named CYP2D6 (cytochrome P450 2D6).
The CYP2D6 enzyme changes codeine into its active form, morphine. Variants in the CYP2D6 gene can make excess enzyme which will cause codeine to change to morphine more quickly and can cause higher than expected levels of morphine in the blood. This may result in a potential overdose of morphine in the mother or her nursing infant. The solution is to take lower than the standard dose of codeine or find an alternative medication not processed by CYP2D6. Individuals with this kind of rapid metabolism are often referred to as “ultra metabolizers.” In addition, individuals can have no active CYP2D6 enzyme, or a reduced amount. These individuals are referred to as “poor metabolizers” or “intermediate metabolizers.” People who have the expected, “normal” amount of CYP2D6 enzymes are referred to as “extensive metabolizers.”
Yes, it possible to be tested for genetic changes in CYP2D6 that cause ultra, poor or intermediate metabolism. About 25-30% of all clinically used drugs are metabolized by CYP2D6. Routine screening is not recommended at this time by the FDA except for a few drugs. Getting tested may have benefits for individuals; however, and may help you and your healthcare provider proactively manage your health and medication (including over the counter and herbal supplement) choices.