Genes and Drugs
Patients differ in response to drugs. This variation can range from potentially life-threatening adverse drug reactions to an equally serious lack of therapeutic efficacy even after taking the standard and safe dose of a drug. As knowledge of the human genome increases, it is becoming widely accepted that genetic differences between individuals play an important role in this variability. To help predict potential variability, physicians are increasingly relying on pharmacogenomics testing to provide important clinical information about the genetic status of their patients.
Pharmacogenomics examines the influence of genetic differences to help understand the clinically relevant variation in drug response. Pharmacogenomics testing applies DNA technology to identify these naturally occurring differences to assist optimization of pharmacotherapy for individual patients. These advances in personalized medicine help get the right drug, to the right patient, at the right dose, at the right time.
Cytochrome P450 (CYP) is a set of proteins that help the body metabolize a wide variety of foreign compounds. Certain genetic variants of CYP450 alter the rate of drug metabolism and may cause increased or decreased drug efficacy or adverse drug reactions. In particular, CYP2D6 and CYP3A4/5 are believed to metabolize-30% of all pharmaceuticals. They are known to be essential for the metabolism of many commonly prescribed opioids including Codeine, Dihydro-codeine, Oxycontin, Hydrocodone.
CYP2D6, CYP3A4/5, and Opioid Metabolism
The ability of a person to metabolize certain opioids is based on the number and functional status of CYP2D6 and CYP3A4/5 genes. Defective genes may lead to impaired metabolism, while gene duplication leads to enhanced drug metabolism. CYP2D6 is well characterized with approximately 12% of the population having a slow acting form of this enzyme (poor metabolizer) and 7% a super-fast acting form (ultra-rapid metabolizer) 35% are carriers of a non-functional CYP2D6 allele, elevating the risk of adverse drug reactions when these individuals are taking multiple drugs.
Breast cancer – cancer that forms in the cells of the breasts
Prostate cancer – cancer in a man’s prostate, a small walnut-sized gland that produces seminal fluid
Basal cell cancer – type of skin cancer that begins in the basal cells
Melanoma – serious type of skin cancer
Colon cancer – cancer of the colon or rectum, located at the digestive tract’s lower end
Lung cancer – cancer that begins in the lungs and most often occurs in people who smoke
Leukemia – cancer of blood-forming tissues, hindering the body’s ability to fight infection
Lymphoma – cancer of the lymphatic system
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