by brant bullard | May 15, 2014 | Metabolic Validation Program
Unlocking the future of medicine
A primary goal of personalized medicine is to provide the best medical treatment for each individual patient by determining which drug will have the best efficacy and have the least amount of toxicity and/or adverse effects. Furthermore, understanding interindividual variations of response to drug treatment, especially in patients with potential adverse reactions, might lead to biomarkers that can be used to predict the low incidence of idiosyncratic toxicity. Individualized medicine is usually based on the concept of pharmacogenomics that studies the influence of an individual’s genotype and/or SNPs on their response to a drug or medical treatment.
When drugs are prescribed, personalized medicine will use metabolic validation testing to predict how individuals will metabolize the compound. One example of this pharmacogenomics approach is the FDA approval of genetic tests that can predict the appropriate starting dose of the blood thinner warfarin (trade name Coumadin).
Because warfarin has a very narrow therapeutic range and because there is high inter- and intra-patient variability in response, finding the optimal dose can be challenging. While there are non-genetic factors that affect individual response, it is known that variations in two specific genes are associated with response to warfarin, and it has been suggested that pharmacogenomic-based dosing could speed up the determination of the appropriate initial therapeutic dose.
Medical School and Pharmacogenomics
Pharmacogenomics has been the major focus area to date; 84% of medical schools in the United Kingdom and 74% of U.S. and Canadian medical schools include pharmacogenomics in their curricula.
Source: Medscape.com
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by brant bullard | May 12, 2014 | Metabolic Validation Program
Before pharmacogenomics, healthcare providers used a “one size fits all” approach to treating individuals.
Now it has the potential to transform healthcare through, avoidance of drug side effects.
Metabolic Validation testing can determine whether you are a poor metabolizer, intermediate or ultra-rapid metabolizer.
The goal of metabolic validation testing (pharmacogenetic testing), is to have drug treatments that are specific to each person.
Today, healthcare providers have the ability to use genomic information to tailor medicine and/or treatments to the individual, and personalize their care.
Nurses are typically on the front line communicating with the patient, family and other healthcare professionals. It is important that they understand the impact and effectiveness of personalized medicine.
A nurse can play a big role in personalized medicine. They can help facilitate drug selection or dosage in treatment of an individual.
In 2007, the FDA revised the label on the common blood-thinning drug warfarin (Coumadin) to explain that a person’s genetic make-up might influence response to the drug. Warfarin and many other drugs now have a Black Box Warning to let healthcare professionals know patients may need to receive a lower dose or to change what medications they are receiving to avoid adverse drug reactions.
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by brant bullard | Mar 31, 2014 | News
Pharmacogenomics is the science of determining how genetic variability influences physiological responses to drugs, from absorption and metabolism to pharmacologic action and therapeutic effect. With increasing knowledge of the molecular basis for a drug’s action has come the recognition of the importance of an individual’s genetic makeup in influencing how he or she may respond to a drug.
Genetic variants in drug metabolizing enzymes can have a significant effect on the way a person responds to a drug. They can speed up or slow down enzymatic activity, or even inactivate an enzyme. In some patients, known as rapid metabolizers, drugs are metabolized too quickly. As a result, the average dose of the drug may be broken down too quickly to be effective, and a higher dose may be needed. Conversely, where the metabolite of the drug is active, as in the case of codeine (see below), rapid metabolism may lead to excessive accumulation of the active metabolite, which may result in toxic levels. In slow metabolizers, a drug administered at the recommended dose can accumulate due to such slow metabolism, potentially reaching toxic levels in the patient’s system and leading to adverse reactions. Such patients may require a smaller dose. In conjunction with other factors, pharmacogenomics offers the potential to enable doctors to identify the patients who are rapid or slow metabolizers of certain drugs and to adjust dosing accordingly to achieve both effective and safe treatment.
- Rapid metabolizers may break down a drug too quickly and require higher doses.
- Slow metabolizers may build up toxic levels of the drug and require smaller doses.
Clinical Applications of Pharmacogenomics
Warfarin (Coumadin and generics), an anticoagulant, is a recent example of the clinical use of pharmacogenomics to improve dosing. Warfarin has a narrow therapeutic window and a wide range of inter-individual variability in response, requiring careful clinical dose adjustment for each patient. Genetic variants in the warfarin target, the vitamin K epoxide reductase (VKORC1), as well as the warfarin metabolizing enzyme, cytochrome P450 2C9 (CYP2C9), influence the variation in patient response. Patients with certain variants of these genes eliminate warfarin more slowly and typically require lower warfarin doses. In those individuals, a traditional warfarin dose would more likely lead to an elevated International Normalized Ratio (INR), a longer time to achieve a stable warfarin dose, and a higher risk of serious bleeding events during the induction or dose-titration period of warfarin therapy. (FDA News)
Another recent example involves ultrarapid metabolizers of codeine, who have multiple copies of the gene for cytochrome P450 2D6 (CYP2D6), the enzyme that converts codeine into morphine, its active metabolite.
Tests to identify the three genetic polymorphisms for warfarin, codeine, and carbamazepine described above are commercially available.
Read more at FDA.com
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PGx Medical
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info@pgxmed.com
405-509-5112
by brant bullard | Mar 23, 2014 | News
In December 2008, the New York Times ran a story about a woman from California who had been taking a drug called tamoxifen to help prevent breast cancer. After two years of taking the drug, her doctor ordered a new genetic test that showed that her genes were preventing the drug from working properly.
“You find out you’ve been taking this medication for all this time, and find out you are not getting benefit…I was devastated” says the women. She had to stop taking tamoxifen. The good news is that she found out that the drug was not helping her and her doctor can now prescribe a drug which will work in her body. The bad news is that she could have known this two years ago if she had taken the genetic test from Day 1.
Experts report that approximately $300 billion is wasted each year on drugs which apparently do not work in people who have certain genes. These people never receive the full benefit from these drugs. Others are getting dangerous side effects.
For example, the blood-thinning drug warfarin is one of the top twenty drugs prescribed in the US. It is used to help prevent blood clots. If a person’s genes prevent the drug from working correctly, warfarin becomes dangerous. It is one of the top three drugs that cause hospitalization or emergency room visits. If a person has genes that allow too much warfarin to get into the bloodstream, the blood cannot clot correctly and the person can have bleeding. On the other hand, if a person has genes that prevent enough warfarin from getting into the bloodstream, the person could develop serious blood clots. The way a person’s body reacts to warfarin, tamoxifen and other drugs depends on differences in their genetic makeup.
Genes provide your body with instructions for making enzymes. Enzymes are needed for your body to break down drugs so your body can get benefit from the medicine. You carry two copies of every gene: one from your mother and one from your father. Differences in these genes can affect the speed of different enzymes you have in your body. This affects how well your body is able to use medicines and how well drugs work in your body. Differences in your enzymes can affect how your body can metabolize (break down) a drug and how long the drug stays your body. Based on what type of genes you carry, you may be:
- a poor drug metabolizer
If you are a “poor metabolizer”, you do not break down drugs well. This may result in too much drug in the body which may lead to a dangerous side effect or even death. In some cases, your body may not be able to break down certain drugs to their working form and therefore the drugs will not work properly.
- an extensive or “normal” drug metbolizer
You metabolize drugs at the normal rate.
- an ultra-rapid drug metabolizer
If you are an “ultra-rapid” metabolizer, this means you break down drugs too fast, causing them to be of no use in the body. If medications do not work properly, conditions such as high blood pressure, blood disorders, and cancer will be left untreated and may even lead to death.
Genetic Tests for Drug Response
Researchers have now found more than 30 types of drug metabolizing enzymes in humans and mostly all of them vary between people.
The three main genetic tests available today include: CYP2D6, CYP2C9, and CYP2C1.
Read entire article at: Consumer Health
For more information on Genetic Drug Testing
(PGx Metabolic Validation Program) contact:
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