Pharmacogenomics: Individualized Medicine Coming Soon to Your Practice

The concept of genetics-based medicine seems simple enough- look a a person's DNA and use it to determine what diseases they are at risk for, the genetic code of their cancer or which medications will work best for them.  But in practice, it is much more complex.  Although I have heard snippets about the developing field of genetics-based medicine, I would like to take a deeper look to understand the concept more thoroughly.  Today, I will focus on pharmacogenomics, the study of how an individual's genes affect the body's response to medications. 

Pharmacogenomics Is a Recent Development, Right?

Well, not really.  Over 60 years ago the discovery was made that each person metabolizes drugs differently.  Physicians noted in the 1950's patients responded differently to muscle relaxants used during anesthesia.  A few patients took abnormally long to recover from the medication's affects.  Patients of African descent, however rapidly metabolized the drug and required it in much higher doses.  Only recently, have we begun to understand the exact mechanism of these genetic variations among patients.  The completion of the mapping of the human genome in 2003 has helped scientists begin to explore individual responses to drugs even further, sparking the recent interest and developments in individualized medicine. 

How Will the Science Behind Pharmacogenomics Help My Patients?

Eventually, researchers hope providers will have the tools to consider an individual's DNA in their prescribing decisions.  With pharmacogenomic technology, scientists will be able to develop more potent medications that are more targeted to specific diseases and with fewer side effects.  By analyzing a patient's genetic profile, providers will match patients with the best drug and dose for their personal needs avoiding adverse drug effects.  This could reduce the 100,000 deaths that occur each year as a result of adverse drug reactions.  Pharmacogenomics could also result in the creation of better vaccines, more capable of standing up to pathogens and easier to produce in massive quantities.

For a more practical look at how this concept will affect your practice, take anti-depressants for example.  Patients respond differently to each drug and may experience side effects on one SSRI but not another.  Imagine if you could look at a patient's DNA and immediately choose the best anti-depressant for their needs without the drawn out trial and error process we use today.  

When Can I Expect to See Genetically Tailored Medications In My Practice?

Pharmacogenomics is already available for limited use and is slowly expanding.  Perhaps the most important discovery in pharmacogenomics is that of cytochrome P450, the liver enzyme responsible for breaking down many classes of drugs.  Individuals with less active forms of cytochrome P450 are more susceptible to drug overdose and negative medication side effects as they do not metabolize drugs as quickly.  Clinical trials are currently using cytochrome P450 genetic testing to screen how individuals are expected to metabolize chemical compounds.  Perhaps, this screening could soon be available to providers.

Another enzyme, TPMT, is responsible for metabolizing certain chemotherapy medications, especially those used in childhood cancers.  Oncologists are currently using genetic testing to screen patients for levels of TPMT to determine appropriate chemotherapy levels.  Cool, huh?

It will be interesting to watch as new genetic tests become available allowing us as nurse practitioners to tailor our treatments specifically to individual patients.  We are certainly practicing at an exciting time!