Whenever we take a drug, whether it’s in injectable or an oral drug it must be cleared from our bodies otherwise it can become toxic to us.

Unfortunately, our ability to clear drugs varies from individual to individual. These different abilities are often related to genetic differences we each have from one another. Doing of drugs are reliant on the average, or largest number of individuals and don’t take into account individual differences in drug clearance rates.

We have many new drugs available today to treat advanced prostate cancer. As with all of the drugs Zytiga clears at a different rate in each individual man. Understanding your individual clearance rate can be important in order to avoid either an excess of drugs in the bloodstream which can become toxic or to make sure that dosage is high enough to have the desired positive effect.

Like many other commonly used drugs, Zytiga operates on an enzyme called CYP2D6. In the general population 5% to 10% of men lack the ability to adequately clear this enzyme from their body. Men who can’t clear it are at risk of a having a toxic response to the drug. On the other hand, almost 5% of men will clear this drug in half the time of the average man. This situation lends itself to a man not having adequate saturation levels of Zytiga and not having the optimum response.

The good news, however often it not discussed, is that it is possible to have a simple genetic screening performed which could tell you your ability to clear this enzyme. Knowing your individual ability to clear Zytiga will help your doctor to see if you will require some dose manipulation to protect you and insure a good response.
Fortunately, this test is generally available from many local labs including LabCorp. Some insurance companies may pay for it, so check with them. If they don’t appeal using the argument that if it becomes toxic they could save money by avoiding possible hospitalizations and if you are a quick processor the drug will not work and they will have wasted their money on an ineffective treatment.

Even if you’re not getting ready to take Zytiga having this to CYP2D6 test (sometimes referred to as the Tamoxifen Test) should be of value to you because of the large number of other drugs, including oxycodone and hydrocodone that operate on this CYP2D6 enzyme.

Joel T. Nowak, M.A., M.S.W.