What is Pharmacogenomics?
The world of medicine is constantly changing, and new drugs are being approved in record numbers. The FDA approved a total of 59 new drugs in 2018. This may not seem like a high number but the last year that the FDA approved over 50 drugs in one year was 1996, making this the highest in at least 25 years. What is more astounding than the number of drugs approved however, is the type of drugs. More and more of the drugs being approved are drugs for personalized medicine, or what is known as pharmacogenomics.
Pharmacogenomics is the study of how a person’s genes affect their response to drugs. This new and emerging science is an area that pharmacists can make a huge role in a patient’s healthcare. This article hopes to explore pharmacogenomics in a little more detail, that way no matter who you are you can understand how pharmacogenomics affects you.
Pharmacogenomics was first identified in 510 BC by Pythagoras. The same guy who was responsible for creating the pythagorean theorem we all blocked from memory as soon as we learned it as teenagers.. He did not call it pharmacogenomics at the time of course. He simply noticed that when some people ate fava beans they had a severe, potentially fatal, reaction, while others did not. It wasn’t until the 1950s that modern science identified this reaction as due to a G6PD deficiency.
After Pythagoras, in 1866, Mendel established the rules of heredity by using pea plants to test for genes. Known as the father of genetics he was able to coin the idea of dominant and recessive traits in plants by creating punnett squares. These squares were another of the many items we forgot during our schooling. While these squares may bring back memories of being back in a classroom for some, they also show just how simple pharmacogenomics can be. These basic principles are still used today. So if you could grasp the concepts behind these squares in school than you can understand pharmacogenomics now.
After Mendel created the idea of genetics, it took several trials and many years until Vogel coined the term pharmacogenetics in 1957. Since this time the expansion of this scientific field has grown exponentially. We have identified the structure of DNA, and know that it is made up of different bases. These bases are largely the same, however variation in the genome is seen every 500-1,000 bases, thus accounting for the difference between humans. These differences can come in many different forms, but the most well studied are known as SNPs or single nucleotide polymorphisms.
These SNPs are a large part of why a drug that works for one person may not work for someone else. In 2000 we were able to complete a map of the human genome sequence variation identifying 1.42 million SNPs. The information we learned from this was invaluable. Now that we know what the differences between the genes are, we can compare those to responses to medications and thus form the basis of pharmacogenomics. Because of this, the first pharmacogenomics test was approved by the FDA in 2005. This tested for variations in two alleles, CYP2D6 and CYP2C19.
To date we have multiple pharmacogenetic tests available that test over 50 genes for potential interactions. According to the FDA, currently there are 214 drugs that have proven, documented drug-gene interactions. When a drug has such a strong drug-gene interaction that it must be included in the package labeling, that means there is a plethora of peer reviewed, researched, and published information out there proving the drug-gene interaction. The majority of this research is only 10 years old.
Some medications can only be prescribed after pharmacogenomic testing has been done. For example, abacavir is used to treat HIV patients, and can only be prescribed after testing for the HLA-B biomarker. If a patient is positive for HLA-B*5701 allele, they could have a potentially fatal hypersensitivity reaction.
Some medications may need to have their doses adjusted based on the results of pharmacogenetic testing. For example Warfarin has drug-gene interactions with both CYP2C9 and VKORC1. The package insert uses a chart that shows how both these genes can cause alterations in the starting dose.
So What Is Next?
This field is so new, and the amount of information we are learning every day is astounding. If you want to keep up with this field I highly recommend checking out the FDA’s website on pharmacogenomics. They are a great resource on this emerging field.
Your physician or your pharmacist should know if you are taking a medication that would require pharmacogenomic testing. However, if you are interested in having yourself tested than simply schedule an appointment with your healthcare provider. These tests are not cheap, however they are becoming so prevalent that they are getting cheaper very quickly. It is also important to consider the privacy of your pharmacogenomic information. Popular home testing kits have had data breaches in the past. So by going through your healthcare provider your information will be more protected than if you did it at home, as it would be part of your protected health information.
Our team member Catlina will be presenting a poster about her research on Pharmacogenomics at the College of Psychiatric and Neurologic Pharmacists Annual Meeting next month! If you have any questions about pharmacogenomics you can always use our contact us page to reach out.
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