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The role of pharmacogenomics 1(1)

Different patients with the same diagnosis and symptoms respond differently to drugs based on their own individual biochemistry, among other factors

Pharmacogenetics explores how a person’s genotype influences the way in which that individual responds to a particular drug.  At the root of pharmacogenetics is the improved “efficacy” of prescribed drugs, or, in other words, making certain that a person with a particular ailment can be prescribed a known effective antidote without experiencing adverse reactions.  Pharmacogenetics is an emergent field that follows in the vein of “individualized medicine”—customizing drug therapy to an individual’s biochemistry; this is a very patient-centric field.

While it has been widely observed that certain individuals with the same disease or symptoms will respond differently to a prescribed drug, the reasoning behind why these different responses occur is significantly more nebulous.  By studying patients who have reacted poorly to a drug versus those that have been aided by the drug, and then comparing the genomes of those individuals for similarities or differences, scientists hope to improve the overall quality of care and treatment the patient receives.

One widely-publicized example of how pharmacogenetics can be employed is in the use of vitamin E supplementation.  Scientists have identified two subsets of diabetes patients (with different genomes) that either received cardiovascular benefits or detriments from ingesting a simple vitamin E supplement.  Based on the particular genetics of an individual, HDL (good cholesterol) can either increase (positive cardiovascular outcome) or decrease (negative cardiovascular outcome) through vitamin E supplementation.  This simple and relatively harmless study of the effects of a dietary supplement on various genomes serves as a basic example for how pharmocogenetic awareness can serve to hurt or help the patient. 

Pharmacogenomics

The two medical specialties that most widely employ the knowledge of pharmacogenetics are oncology (the treatment of cancer) and psychiatry.  Because oncologists administer and prescribe a significant number of drugs to their patients, and because of the grave nature and rapid proliferation of most cancers, it is essential that the drugs given be not only effective, but also possess the fewest side-effects as possible.  By identifying genetic characteristics that might make an individual respond adversely to a particular cancer drug, the doctor can help the patient avoid any unnecessary pain or setbacks in his or her treatment.  Similarly, psychiatrists are also heavy prescribers, dolling out myriad phsychotropic drugs to their patients until an optimal level of treatment is reached.  Oftentimes, finding the right drug combination to treat an individual’s depression, for example, is a matter of trial and error.  However, by employing pharmacogenetics and analyzing a person’s constitution before administering a drug, the psychiatrist is able to cut down on the “trial” period and provide the patient with effective treatment earlier on.

Whereas in the past, identifying a person’s genetic makeup was a much more daunting, laborious and expensive undertaking, today it has become quite accessible for individual’s and doctors to access genetic information, and use that information to create a customizable treatment plan.  All that is needed is a saliva or peripheral blood sample, and someone with the knowledge to effectively interpret and apply the results.

The field of pharmacogenetics is an increasingly-important one, as millions of deaths occur annually due to adverse drug reactions, and still millions more from mistreating diseases with ineffective drugs. Again, the overall goal in the field of pharmacogenetics is to be able to tailor a drug (and therefore the drug's effectiveness) to an individual's genetic makeup, providing a form of assurance that the prescribed medicine will produce the desired outcome for the patient.

Of note is the often-interchangeable nomenclature of the terms pharmacogenetics and pharmacogenomics. While the terms are sometimes used synonymously, the former focuses on how specific drugs react with a particular individual's biochemistry, while the latter tends to refer to techniques in discovering how a person responds to a drug, and is therefore more technical and specific.

References:

Chadwick, Ruth.  Encyclopedia of Applied Ethics (2nd edition).  “Pharmacogentics,” (2012), pages 438-442.

Chiara, Fabbria, Alessandro, Minarinia, Yoshihiko, Matsumotob, Alessandro Serretti.  Handbook of Pharmacogenomics and Stratified Medicines (2014), pages 543-562.

Farbstein D, Blum S, Pollak M, Asaf R, Viener HL, Lache O, Asleh R, Miller-Lotan R, Barkay I, Star M, Schwartz A, Kalet-Littman S, Ozeri D, Vaya J, Tavori H, Vardi M, Laor A, Bucher SE, Anbinder Y, Moskovich D, Abbas N, Perry N, Levy Y, Levy AP (November 2011). "Vitamin E therapy results in a reduction in HDL function in individuals with diabetes and the haptoglobin 2-1 genotype". Atherosclerosis 219 (1): 240–4. doi:10.1016/j.atherosclerosis.2011.06.005. PMC 3200506. PMID 21722898.

Jacques, Robert.  European Journal of Cancer, “On the use of pharmacognetics in cancer treatment and trials” (August 2014).

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