Personalized Medicine and The Pharmacist

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What is the role of pharmacists in personalized medicine?

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Personalized medicine is a new field of pharmacy that involves individualizing drug therapy according to a patient’s genetic profile. Since pharmacists are drug experts, pharmacists should be at the forefront of personalized medicine. Therapeutic drug monitoring currently involves measuring the plasma drug concentration of a patient to determine an individualized dose in order to decrease side effects and maximize efficacy, leading to shorter hospital stays and reduced costs. As such, this practice is now common in most hospitals. If the practice of personalized medicine is coupled with current pharmacokinetic monitoring, this will achieve more positive therapeutic outcomes.

Because this idea is quite new, there are still some issues to be resolved before it can be widely accepted. One major concern is the cost of running genetic tests. Genetic tests are known to be very expensive and can vary widely depending on the types of protocol used, size and number of genes being tested, and equipments needed for the test. Genetic tests are generally more labour intensive since they need experts to interpret the data and then determine a customized regimen tailored to specific genetic profiles. For example, a sequencing test may cost as much as $500 to $3000. This price definitely needs to be lowered before personalized medicine can become practical.

A pharmacist’s role in medicine is to take all of the information available regarding a patient, and use it to recommend the safest and most effective treatment plan. Currently pharmacists can use a patient’s past medical history; various lab values; physical characteristics of the patient such as height, weight, sex; and patient preferences in order to recommend an optimal drug and dosage regimen. Sometime in the near future a pharmacist will have access to each patient’s sequenced genome, which will add one more piece of information that can be used to make a therapeutic recommendation. The genome will tell the pharmacist a number of things. It may tell them that a patient is more likely to contract cancer, or heart disease – not particularly useful when deciding what medication to take for a bacterial infection or a migraine. The genome may tell the pharmacist that a patient lacks a certain enzyme used to metabolize a drug, or possibly that the patient has extra drug-metabolizing enzyme. This information will be most useful. The current model for determining the correct dose of a drug is essentially a trial and error affair, which works fine in most cases with the obvious downside being the “error” part. Every once in a while someone is given a drug that should be safe and for some reason it isn’t. In these cases (excluding certain allergic reactions) the basis of the unexpected action of a drug is often genetic. With good access to the genetic information of a patient these dangerous situations could be avoided. This should result in fewer doctors visits, fewer trips to the emergency department, and fewer deaths while promoting favorable therapeutic outcomes.

It is clear that pharmacogenomics has a significant role in therapeutics. However, how feasible is its incorporation into current pharmacy practice? In United States, several drugs like mercaptopurine, irinotecan, cetuximab, trastuzumab, abacavir, clopidogrel and warfarin have recently been FDA approved to include genetic information in the labeling to assist dosing. Furthermore, the Clinical Laboratory Improvement Amendments of 1988 has allowed easier access to genotype testing. These steps have allowed St. Jude Children’s Research Hospital to implement a successful clinical pharmacogenetics service that can serve as a framework for future practicing pharmacists.

As mentioned earlier, this is a new concept that has recently been experimented in the health-care field with many issues and concerns that need to be resolved. But when this new area of practice is implemented with full-force in the field, what exactly will the experts be accomplishing? As the pharmacist learns to characterize the relationship between the changes in our genome with our ability to respond to and/or metabolize a specific drug, they can use that information to analyze individuals with single-nucleotide polymorphisms (SNPs) and their ability to metabolize, transport, or respond to certain drugs. This will, as a result, shift from the standard reference dosing from a textbook to a more individualized dosing, therefore tailoring it to a patients’ phenotype and maximizing the benefit of their drug therapy. In addition, as the pharmacist begins to understand that certain individuals have different SNPs in their genome, they begin to understand why different individuals have varying responses to the same drug. The drug-experts can then aim to overcome this individual variance by altering the doses of medications to make sure a patient receives the most safe (by preventing ADRs) and effective therapy.

Personalized medicine is the way of the future as technology improves and we learn more about our genome. As medication experts, pharmacists have the knowledge and ability to play an important role in individualized therapy decisions. Using genetics to make therapeutic decisions will lead to more positive therapy outcomes and less adverse drug reactions. However, there is still a lot to determine with regards to how this model will be implemented and whether or not it will be feasible.  

Written by smo

February 2nd, 2012 at 12:33 pm

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