Pharmacology for the Clinical Chemist: Therapeutic Drug Monitoring and Pharmacogenomics

Author: Kevin F. Foley, PhD, DABCC, MT, SC
Reviewers: Robert E. Moore, MLS(ASCP)CMSCCM, TC(NRCC) and Laurie Bjerklie, MA, MLS(ASCP)CM
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Continuing Education Credits

P.A.C.E.® Contact Hours: 2 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Clinical Chemistry/UA/Toxicology): 1.5 hour(s)

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Therapeutic drug monitoring and pharmacogenomics are both pharmacy-related areas within the clinical laboratory. Although each is considered a sub-discipline within laboratory medicine, the two fields overlap significantly. This course provides an overview of each of these laboratory sub-disciplines and discusses the utility, rationale, and practice of each one. The course is intended for clinical laboratory technologists and technicians and other health care personnel who are responsible for prescribing and administering therapeutic medications.

Objectives

  • Define therapeutic drug monitoring and explain the rationale for this testing.
  • Explain the concept of elimination half-life.
  • List the criteria and attributes of commonly monitored drugs.
  • Discuss three methods that are used for the measurement of therapeutic drugs in serum.
  • Define pharmacogenomics, polymorphism, CYP450, and personalized medicine.
  • Explain the usefulness of CYP450 testing as well as its shortcomings.
  • State the four classifications of metabolizers and the clinical relevance of each.

Course Outline

  • Therapeutic Drug Monitoring
    • Introduction
    • Therapeutic Drug Monitoring Definition
    • Pharmacogenomics Definition
    • Basic Pharmacokinetics
    • Drug Concentration Over Time
    • Drug Metabolism
    • Drug Elimination
    • Half-Life
    • Bioavailability
    • Protein Binding
    • Protein Availability and Drug Dosing
    • Other Factors Affecting Drug Absorption and Distribution
    • Given what you have learned thus far, which of the following statements below is true?
    • Steady State
    • Steady State Example
    • Sampling
    • Peak and Trough Sampling Times
    • Why Therapeutic Drug Monitoring?
    • Therapeutic Window
    • Unexpected Concentrations
    • Match each of the definitions shown below with the term from the drop-down box that it defines.
    • A physician needs to prescribe a drug to a patient, but the drug has a narrow therapeutic window. The physician is concerned about possible toxic effects. To assess the upper concentration of such a drug, which time do you think makes the most sense for drawing the specimen?
    • Do All Drugs Benefit From Therapeutic Drug Monitoring?
    • When is Therapeutic Drug Monitoring Not Useful?
    • Alternatives to Therapeutic Drug Monitoring
    • Examples of Drugs Monitored by Therapeutic Drug Monitoring
    • Antibiotics
    • Anticonvulsants
    • Immunosuppressants
    • Cardiac Medications
    • Theophylline
    • Albuterol is a fast-acting bronchodilator used acutely during asthma attacks. Which of the reasons below would best explain why TDM for albuterol is not available or common?
    • Laboratory Methods
    • Chemiluminescence
  • Pharmacogenomics
    • Personalized Medicine
    • Polymorphism and Cytochrome P450
    • CYP450 Enzymes
    • CYP2D6 Enzyme
    • Metabolizers
    • Enzyme Abnormalities and Drugs
    • Clinical Utility
    • Warfarin Metabolism
    • Warfarin Metabolism, continued
    • If a person is classified as an ultrarapid metabolizer (UM), how much of a drug would they need?
    • CYP450 Induction and Inhibition
    • Table 5: CYP450 Inducers and Inhibitors
    • A patient is taking cimetidine for a stomach ulcer. This drug inhibits CYP2D6. The patient is now prescribed amphetamine for narcolepsy. Amphetamine is metabolized by CYP2D6. What would you predict?
    • Genotype versus Phenotype
    • Genotype versus Phenotype, continued
    • Can Therapeutic Drug Monitoring Assess Pharmacogenetics?
    • The Bottom Line
    • The Bottom Line, continued
  • References
    • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical laboratory technicians, laboratory supervisors and managers, as well as other health care personnel who are responsible for prescribing and administering therapeutic medications. This course is also appropriate for MLS and MLT students and pathology residents.
Author Information: Kevin F. Foley, PhD, DABCC, MT, SC, is the director of clinical pathology for the Kaiser Permanente Northwest region. He also teaches clinical chemistry at Oregon Health Sciences University. Dr. Foley earned his PhD in clinical pharmacology and toxicology at the East Carolina School of Medicine in North Carolina. He received a PhD in clinical pharmacology and toxicology from Brody School of Medicine, Greenville, NC. He has been working in laboratory medicine for over 15 years, starting his career as a medical technologist.
Reviewer Information:
Robert E. Moore, MLS(ASCP)CMSCCM, TC(NRCC) is the lead technologist in the toxicology laboratory at Kaiser Permanente in Portland, Oregon, where his responsibilities include methods development and validation, review of QC data, instrument troubleshooting, and employee training/competency assessment. In his career as a medical laboratory scientist, he has been a chemistry supervisor, toxicology supervisor, and laboratory director. He holds a Bachelor's degree in Biology from Marshall University.
Laurie Bjerklie, MA, MLS(ASCP)CM, is currently an Education Developer for MediaLab and LabCE. She earned a B.S. in Medical Laboratory Science from the University of North Dakota and an M.A. in Curriculum and Instruction from Saint Xavier University. She has over 15 years of experience in higher education and has held program director and faculty positions in both MLT and MLS programs.