California Pharmacist - Summer 2012 - (Page 26)
Pharmacogenomic Testing in an HIV Clinic
By Sarah McBane, PharmD, CDE, BCPS; Nathan Painter, PharmD, CDE; and Craig Ballard, PharmD Introduction
Pharmacogenomics is a study of genome-wide variations of genetic determinants for drug efﬁcacy and toxicity. This includes genes that encode for drug receptors, metabolizing enzymes and transporters, as well as genes involved in disease susceptibility that can affect drug response.1 Also known as “personalized medicine,” pharmacogenomics has the potential to match a drug to an individual’s response in order to minimize toxicity and maximize effectiveness. This would allow healthcare practitioners to tailor drug treatments. For patients, a greater conﬁdence in their prescribed drug therapy may lead to higher adherence rates and a more efﬁcient healthcare system. In 2002, researchers observed that abacavir hypersensitivity occurred in patients carrying the HLA-B*5701 allele, which occurs in 4-5% of the patients being treated with abacavir.2,3 Because of this, the ﬁrst large international pharmacogenomic randomized clinical trial was published in 2008 and demonstrated that screening for HLAB*5701 before starting abacavir therapy and avoiding the drug in patients that carry the HLA-B*5701 allele resulted in the disappearance of the hypersensitivity reaction. This pharmacogenetic test is now routinely ordered when providers prescribe abacavir.4 practitioners, social workers, nutritionists and mental health workers. The pharmacist-directed antiretroviral clinic within the Owen Clinic was established in 1987 when zidovudine (AZT) was FDA approved. At the clinic, pharmacists have their own schedule of patients and provide medication therapy management, adherence counseling, assistance with medication access and other duties. Since 2007, the pharmacists in the Owen Clinic have been ordering the HLA- B*5701 genetic test to assess appropriateness of abacavir use in the designed antiretroviral regimens for patients. This is part of the pharmacists’ role in starting or changing antiretroviral therapy in the clinic. The pharmacists maintain a log of test results and enter the results into the patient’s electronic medical record. Since 2007, over 700 results have been collected and documented. The result is used to determine if an abacavircontaining regimen would be appropriate for the patient. If the HLA-B*5701 allele is present, then the patient’s allergy proﬁle is updated and abacavir is avoided due to the increased risk of a hypersensitivity reaction.
and the HIV/Hepatitis C co-infection clinics within the Owen Clinic.
Descriptions of Successes
Since the HLA-B*5701 testing has been implemented, the Owen Clinic has seen no hypersensitivity reactions in patients, thus avoiding many potential emergency department visits. Prior to implementation of the testing, anytime a patient was presented with signs and symptoms suspicious of an abacavir hypersensitivity reaction, all antiretroviral therapy would be discontinued. Even though speciﬁc cause of the reaction was unclear, many patients lost the opportunity to be considered for several other potential antiretrovirals. Prior to use of the HLA-B*5701 test, practitioners often estimated that around 10 percent of patients would experience an abacavir hypersensitivity reaction. Since implementation of the testing, only about 5 percent of patients were found to actually express the HLA-B*5701 allele.
There are three pharmacists sharing two full-time positions. Each pharmacist has a dedicated exam room for patient encounters. The pharmacist’s clinic schedule includes six patients per half-day, and each patient has a 30 minute visit. Additionally, student pharmacists and residents participate in the patient care and present patient cases to the attending pharmacist in the clinic. The pharmacists work under a collaborative practice protocol to manage patients in the antiretroviral
Limitations of the Model
The HLA-B*5701 test results take ﬁve to seven days to become available to the pharmacists or other providers. Abacavir cannot be initiated during this time frame. Because the test is not performed in house, the test results are not directly imported into the health system’s electronic medical record and must be manually entered into a spreadsheet. Relevant allergy information (which would preclude use of abacavir) must be manually entered
Description of the Practice Model
The Owen Clinic is a HIV/AIDS clinic within the University of California, San Diego (UC San Diego) Health System. The Owen Clinic utilizes an interprofessional health care team which includes physicians, pharmacists, physician assistants, nurse
CALIFORNIA PHARMACIST | SUMMER 2012 | www.cpha.com
Table of Contents for the Digital Edition of California Pharmacist - Summer 2012
From the Editor
From the President
Pharmacogenomics, Diagnostics & Evaluation – the Pharmacist’s Role
Overview Update of Pharmacogenomics and Disease Genetic Testing
Pharmacogenomic Testing Technology in Currently Available Test Kits
Pharmacogenomic Testing in an HIV Clinic
Pharmacogenomic Testing at the VA San Diego Healthcare System
Pharmacists and Pharmacogenomics: An evaluation of knowledge, beliefs, attitudes and practices
Pharmacy Quality Commitment helps Pharmacists Meet the Demands of Continuous Quality Improvement
Brilinta® Ticagrelor: Another Option in Antiplatelet Therapy
A Summer Half-Helix Sale
Index to Advertisers
California Pharmacist - Summer 2012
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