What’s Ahead for Post-acute Care Pharmacy: Pharmacogenetics & Anticoagulation Therapy

The field of medicine is continually changing, and with it, so is long-term care pharmacy. As researchers uncover more about how the body works and metabolizes medications, the potential to personalize those medications—and optimize results—grows. The topic of pharmacogenetics is increasing in popularity as we progress toward personalized medicine. We have learned a significant amount about how an individual’s genetic makeup impacts how medications are metabolized, which affects the efficacy and safety of a medication. The missing link in most situations is knowing and understanding each Skilled Nursing Facility’s resident’s genetic makeup so that we can relate that to the therapies that a resident is receiving or may be receiving in the future. That’s where post-acute care pharmacy will continue to evolve.

The Potential Role of Pharmacogenetic Testing in Post-acute Care Pharmacy

Pharmacogenetic testing has the ability to provide healthcare practitioners with this valuable piece of information. Knowing a resident’s genetic makeup gives providers the potential to be able to predict potentially dangerous adverse reactions, identify therapies that may not be effective, and prevent unnecessary hospitalizations caused by these ill effects. While pharmacogenetic testing is far from routine practice at this time, there are specific situations when it may want to be considered, including with anticoagulation and antiplatelet therapy. Adverse drug events and medication nonadherence are a leading cause of hospitalization among seniors. The majority of emergency hospitalizations caused by drug events are associated with five specific types of medications: warfarin, insulin, oral antiplatelets, diabetic medications, and opioid pain medications. As we work to reduce unnecessary hospitalizations, we are finding ourselves having to look outside of the box more and more to find the root cause of medication-related issues. [Tweet “The potential role of #pharmacogenetics in #postacutecarepharmacy”]

How Pharmacogenetics Could Benefit Anticoagulant Therapy in Post-acute Care Pharmacy

Clopidogrel, known by its brand name Plavix®, is a widely used antiplatelet medication in long-term care pharmacy. Pharmacogenetics is a pertinent topic related to clopidogrel because clopidogrel is a prodrug, a type of medication which must be metabolized through the cytochrome P450 system before it becomes an active medication. If a resident’s cytochrome P450 enzyme system is not functioning as expected, this will result in variability in the metabolism of clopidogrel, which ultimately means the medication may not be metabolized to the active form.

In short, we could be administering the medication to the resident exactly as ordered, but the body may not be reacting to it the way we expect. Pharmacogenetic testing would allow us to know if an resident’s cytochrome P450 system is functioning as expected prior to prescribing the medication.

Warfarin, or Coumadin®, is another key example. Warfarin has a number of potential interactions with both foods and other medications. In addition, warfarin can also be very difficult to stabilize in some residents.

The difficulty in stabilization could be caused by two different situations. First, warfarin is significantly metabolized by the cytochrome P450 system, so variations in a resident’s cytochrome P450 system detected through pharmacogenetic testing could impact the plasma levels and clearance of warfarin in the body.

Warfarin is also unique because of the VKORC1 enzyme, which controls the oxidation state of vitamin K. VKORC1 normally works to activate vitamin K as part of the normal clotting cascade. Warfarin inhibits VKORC1, which reduces vitamin K oxidation and reduces clotting. If a resident has lower levels of VKORC1, less warfarin will be needed to affect the clotting cascade. If this is not known and a resident receives a standard dose of warfarin, he or she may experience an increased risk of side effects, such as bruising and bleeding.

If pharmacogenetic testing was used, clinicians would have cytochrome P450 and VKORC1 genetic information available to them at the time of prescribing. This would allow them more appropriately prescribe a dose of medication to the resident that will be best suited for his or her body to optimize effectiveness and minimize adverse effects.

As mentioned earlier, pharmacogenetic testing is not standard of care at this point in time. However, there are valid reasons, such as with antiplatelet and anticoagulation therapy, which could make this type of testing more common.

Once a person has pharmacogenetic testing conducted, it does not need to be done repeatedly. The results of the testing can be applied to the resident’s entire therapeutic regimen and taken into consideration prior to future prescribing to make his or her medication regimen more targeted and personalized.

As healthcare providers, we encounter many situations that just don’t make sense or where we can’t figure out why something isn’t working as expected. This is because of the human body and factors that we cannot see with the naked eye. In the future, with pharmacogenetics, we’ll be armed with the extra tools we need to make optimal decisions for our residents.\

Pharmacy is always evolving, and we work to stay ahead of the changes. Grane Rx offers the Medication Insights™ program, powered by YouScript, to help identify potential interactions and offer alternative prescribing options. To learn more or request a free analysis, visit www.MedicationInsights.com.

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