Mohamad-Ali Salloum is a Pharmacist and science writer. He loves simplifying science to the general public and healthcare students through words and illustrations. When he's not working, you can usually find him in the gym, reading a book, or learning a new skill.
Unlocking the Future of Medicine: An In-Depth Exploration of Pharmacogenomics
Mohamad-Ali Salloum, PharmD • December 9, 2023
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Understanding Pharmacogenomics:
The world of pharmacology is continually evolving, and one of the most exciting frontiers is Pharmacogenomics. Usually, we treat patients based on their clinical characteristics. But with pharmacogenomics, we take into consideration the genetic variability of drug metabolism and response within each person. This allows us to exactly treat what the patient is suffering from, and at the same time reduce some of the unwanted side effects in some cases.
What are the implications of PG in Pharmacy Practice?
1. Individualized Treatment Plans:
Warfarin, an anticoagulant, poses challenges due to its narrow therapeutic window. Pharmacogenomic testing can identify variations in genes like CYP2C9 and VKORC1, influencing an individual's response to warfarin. This genetic insight enables healthcare professionals to determine the most effective and safe dosage for each patient, reducing the risk of bleeding or clotting events.
2. Prevention of Adverse Reactions:
By identifying genetic factors that may contribute to adverse drug reactions, pharmacogenomics helps prevent unnecessary complications, enhancing patient safety. This proactive approach aligns with the core principle of pharmacy practice: first, do no harm.
3. Optimizing Drug Selection:
Understanding a patient's genetic profile enables pharmacists to choose medications with the highest likelihood of efficacy. This approach reduces the need for trial-and-error approaches, streamlining the medication selection process and enhancing overall patient care. This is important, especially in the time-sensitive cases of cancer patients where they require the most effective treatment as soon as possible to counteract the cancer invasion.
Challenges and Future Directions:
While the promise of Pharmacogenomics is undeniable, there are some challenges that stops it from being used as frequently as it should be such as:
- Cost,
- Accessibility,
- Need for the broader genetic databases.
I listed below some of the examples to help you understand how PharmacoGenomics can contribute to better management of the patient’s disease.
1. Warfarin Dosing:
Warfarin, an anticoagulant, poses challenges due to its narrow therapeutic window. Pharmacogenomic testing can identify variations in genes like CYP2C9 and VKORC1, influencing an individual's response to warfarin. This genetic insight enables healthcare professionals to determine the most effective and safe dosage for each patient, reducing the risk of bleeding or clotting events.
2. Clopidogrel Metabolism:
Clopidogrel, an antiplatelet medication, requires activation by the enzyme CYP2C19. Genetic variations in the CYP2C19 gene can lead to reduced drug activation, affecting the drug's effectiveness in preventing blood clots. Pharmacogenomic testing empowers clinicians to make informed decisions about alternative antiplatelet medications for individuals with specific genetic profiles, optimizing cardiovascular care.
3. Codeine Metabolism:
Codeine, an opioid analgesic, undergoes metabolism to its active form through the enzyme CYP2D6. Some individuals possess genetic variations that result in poor metabolism of codeine, leading to inadequate pain relief. Pharmacogenomics can identify patients who may require alternative pain management strategies, preventing ineffective treatment and potential adverse reactions.
4. Allopurinol and HLA-B Gene:
Allopurinol, used in the management of gout, is associated with a potentially severe adverse reaction known as Stevens-Johnson Syndrome (SJS). The risk of developing SJS is significantly increased in individuals with a specific variant of the HLA-B gene. Pharmacogenomic testing can identify patients at higher risk, allowing healthcare providers to consider alternative gout medications to minimize the risk of this life-threatening reaction.
Conclusion:
The journey into Pharmacogenomics is an ongoing exploration, and your role as future pharmacists is pivotal. With each step, you are not just studying pharmacology; you are becoming architects of a healthcare future that truly puts the patient at the center. Embrace the possibilities, navigate the challenges, and let the principles of Pharmacogenomics guide your path toward a future where the right drug, for the right patient, at the right time becomes more than a mantra—it becomes a reality.
References:
1. Johnson JA. Pharmacogenetics: potential for individualized drug therapy through genetics. Trends Genet. 2003;19(11):660-666.
2. Relling MV, Evans WE. Pharmacogenomics in the clinic. Nature. 2015;526(7573):343-350.
3. Scott SA, Sangkuhl K, Gardner EE, et al. Clinical Pharmacogenetics Implementation Consortium guidelines for CYP2C19 genotype and clopidogrel therapy: 2013 update. Clin Pharmacol Ther. 2013;94(3):317-323.
4. Stanek EJ, Sanders CL, Taber KA, et al. Adoption of pharmacogenomic testing by US physicians: results of a nationwide survey. Clin Pharmacol Ther. 2012;91(3):450-458.
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Mohamad-Ali Salloum, PharmD
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References: Wood W, Quinn JM, Kashy DA. Habits in everyday life: Thought, emotion, and action. J Pers Soc Psychol . 2002;83(6):1281–1297. Wood W, Neal DT. The habitual consumer. J Consum Psychol . 2009;19(4):579–592. Neal DT, Wood W, Labrecque JS, Lally P. How do habits guide behavior? Perceived and actual triggers of habits in daily life. J Exp Soc Psychol . 2012;48(2):492–498. Wood W, Mazar A, Neal DT. Habits and goals in human behavior: Separate but interacting systems. Perspect Psychol Sci . 2021;16(1):1–16. Graybiel AM. Habits, rituals, and the evaluative brain. Annu Rev Neurosci . 2008;31:359–387. Smith KS, Graybiel AM. Habit formation. Dialogues Clin Neurosci . 2016;18(1):33–43. Yin HH, Knowlton BJ. The role of the basal ganglia in habit formation. Nat Rev Neurosci . 2006;7(6):464–476. Graybiel AM. The basal ganglia and chunking of action repertoires. Neurobiol Learn Mem . 1998;70(1–2):119–136. Schultz W. Dopamine reward prediction error coding. Dialogues Clin Neurosci . 2016;18(1):23–32. Schultz W, Dayan P, Montague PR. A neural substrate of prediction and reward. Science . 1997;275(5306):1593–1599. Nasser HM, Calu DJ, Schoenbaum G, Sharpe MJ. The dopamine prediction error: Contributions to associative models of reward learning. Front Psychol . 2017;8:244. Kahnt T, Schoenbaum G. The curious case of dopaminergic prediction errors and learning associative information beyond value. Nat Rev Neurosci . 2025;26:169–178. Lally P, van Jaarsveld CHM, Potts HWW, Wardle J. How are habits formed: Modelling habit formation in the real world. Eur J Soc Psychol . 2010;40(6):998–1009. American Psychological Association. Harnessing the power of habits. Monitor Psychol . 2020;51(8):78–83.
References: Baddeley A. Working memory: theories, models, and controversies. Annu Rev Psychol . 2012;63:1–29. Chai WJ, Abd Hamid AI, Malin Abdullah J. Working memory from the psychological and neurosciences perspectives: a review. Front Psychol . 2018;9:401. Rogers RD, Monsell S. Costs of a predictable switch between simple cognitive tasks. J Exp Psychol Gen . 1995;124(2):207–231. Rubinstein JS, Meyer DE, Evans JE. Executive control of cognitive processes in task switching. J Exp Psychol Hum Percept Perform . 2001;27(4):763–797. Garner KG, Dux PE. Knowledge generalization and the costs of multitasking. Nat Rev Neurosci . 2023;24:98–112. Zhou X, Lei X. Wandering minds with wandering brain networks. Neurosci Bull . 2018;34(6):1017–1028. Sorella S, Crescentini C, Matiz A, et al. Resting‑state default mode network variability predicts spontaneous mind‑wandering. Front Hum Neurosci . 2025;19:1515902. Sweller J. Cognitive load during problem solving: effects on learning. Cogn Sci . 1988;12(2):257–285.
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References: McMurray JJV, Packer M, Desai AS, et al. Angiotensin–neprilysin inhibition versus enalapril in heart failure. N Engl J Med . 2014;371(11):993–1004. Barter PJ, Caulfield M, Eriksson M, et al. Effects of torcetrapib in patients at high risk for coronary events. N Engl J Med . 2007;357:2109–2122. Kastelein JJP, Akdim F, Stroes ESG, et al. Simvastatin with or without ezetimibe in familial hypercholesterolemia. N Engl J Med . 2008;358:1431–1443. Gerstein HC, Miller ME, Byington RP, et al. Effects of intensive glucose lowering in type 2 diabetes. N Engl J Med . 2008;358:2545–2559. Echt DS, Liebson PR, Mitchell LB, et al. Mortality and morbidity in patients receiving encainide, flecainide, or placebo. N Engl J Med . 1991;324:781–788. Packer M, Anker SD, Butler J, et al. Effect of empagliflozin on cardiovascular and renal outcomes. N Engl J Med . 2020;383:1413–1424. Ioannidis JPA. Surrogate endpoints in clinical trials: are we being misled? BMJ . 2013;346:f314.
References: Wager TD, Atlas LY. The neuroscience of placebo effects: connecting context, learning and health. Nat Rev Neurosci . 2015;16(7):403‑18. Frisaldi E, Shaibani A, Benedetti F, Pagnini F. Placebo and nocebo effects associated with pharmacological interventions: an umbrella review. BMJ Open . 2023;13:e077243. Colloca L, Finniss D. Nocebo effects, patient‑clinician communication, and therapeutic outcomes. JAMA . 2012;307(6):567‑8. Howard JP, Wood FA, Finegold JA, et al. Side effect patterns in a blinded, randomized trial of statin, placebo, and no treatment. N Engl J Med . 2021;385(23):2180‑9. Penson PE, Mancini GBJ, Toth PP, et al. Introducing the “drucebo” effect in statin therapy. J Cachexia Sarcopenia Muscle . 2018;9(6):1023‑33. Barnes K, Faasse K, Geers AL, et al. Can positive framing reduce nocebo side effects? Front Pharmacol . 2019;10:167. Caliskan EB, Bingel U, Kunkel A. Translating knowledge on placebo and nocebo effects into clinical practice. Pain Rep . 2024;9(2):e1142. von Wernsdorff M, Loef M, Tuschen‑Caffier B, Schmidt S. Effects of open‑label placebos in clinical trials: a systematic review and meta‑analysis. Sci Rep . 2021;11:3855.
References: Zaniletti I, Larson DR, Lewallen DG, Berry DJ, Maradit Kremers H. How to distinguish correlation from causation in orthopaedic research. J Arthroplasty. 2023;38(4):634–637. Rush J, Ajami M, Look KA, Margolis A. Statistics review part 10: causality and confounding. J Pharm Soc Wis. 2014;17(1):45–52. Koopmans E, Schiller C. Understanding causation in healthcare: an introduction to critical realism. Qual Health Res. 2022;32(8–9):1207–1214. Kahlert J, Gribsholt SB, Gammelager H, Dekkers OM, Luta G. Control of confounding in the analysis phase – an overview for clinicians. Clin Epidemiol. 2017;9:195–204. Shi AX, Zivich PN, Chu H. A comprehensive review and tutorial on confounding adjustment methods for estimating treatment effects using observational data. Appl Sci (Basel). 2024;14(9):3662. Gao Y, Xiang L, Yi H, Song J, Sun D, Xu B, et al. Confounder adjustment in observational studies investigating multiple risk factors: a methodological study. BMC Med. 2025;23:132. Ho FK, Brown J, Galwey NW. Regression adjustment for causal inference. BMJ Med. 2025;4:e000816. Correia LCL, Mascarenhas RF, Menezes FSC, Oliveira Junior JS, Vaccarino V, Ross JS, et al. Confounder selection in observational studies in high‑impact medical and epidemiological journals. JAMA Netw Open. 2025;8(7):e2524176.