Personalized Medicine and The Pharmacist

Translating the Prescription Encoded in Your DNA: A Personalized Approach to Drug Therapy

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What is personalized medicine?
Traditionally, doctors would prescribe a standard dose of medication for a patient with a particular disease, with the hope that the drug would have the same therapeutic and safety profiles in their patient as it did in the average patient.  However, for most drugs, there are always the unlucky few who experience a diminished therapeutic effect or a dangerous toxic effect that is not seen in the general population.  Now that genomic research has shown that patient variations in drug response can be predicted based on their genetic sequence, all it takes is a genetic test to determine whether a patient would be expected to respond “normally“ to a drug, or experience an exaggerated adverse effect or a subtherapeutic effect.  Dubbed personalized medicine, the process of testing an individual for known gene variations allows pharmacists to determine if the patient has a different form of the enzyme that metabolizes the drug, the protein that transports the drug, or the receptor to which the drug acts on.  Based on these results, the pharmacist can predict how the patient will respond to normal doses of the drug, and can adjust the medication dosing accordingly.For example, a patient who possesses a variation of the enzyme metabolizing drug A, which causes the patient to metabolize or break down the drug slower than normal, will have more of drug A build up in their body due to the inability to metabolize the drug as effectively as the normal patient.  If a pharmacist knows that the patient has the genotype that gives rise to this slow metabolizing enzyme, the pharmacist can give the patient a lower-than-normal dose of drug or recommend that the drug be administered less frequently to the patient so that the patient does not experience toxic effects from the unusually high buildup of the medication in his or her body.

Should pharmacists be involved and if so, what should they do?
Personalized medicine is founded on patient variations in drug disposition, rather than in disease state or diagnosis. Pharmacists specialize in drug disposition, so if personalized medicine is to become the norm in health care, it is pharmacists, not physicians, who need to play the most significant role.


So what kinds of activities would a pharmacist be undertaking in order to offer pharmacogenetics services?
The scope of pharmacy practice is expanding to provide the community with patient-centred care. Pharmacists are now conducting medication reviews and providing more comprehensive counselling services. As an extension, pharmacists can have an active role in providing pharmacogenetic services to patients. Tasks would include conducting critical appraisal of evidence for new technologies and treatments, collaborating with medical laboratories to interpret biological test results (e.g., drug levels in the blood or genetic sequencing information), and making appropriate recommendations to physicians about any changes to drug therapy based on those test results. Pharmacists will also be counselling patients on their personalized drug therapy to ensure they receive optimal benefit from their medication, and understand the rationale behind the recommended drug and dosage regimen.

What does this mean for practicing pharmacists and students?
Some form of clinical case-based learning workshops will have to be developed for practicing pharmacists to familiarize themselves with the requirements associated with providing pharmacogenetics services. Existing undergraduate courses concerning genetics will have to be reviewed; modifications will have to be made to prepare future pharmacists.

Written by jbelle

February 2nd, 2012 at 12:31 am

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