Basics of Drug Interactions
38 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

A patient's TSH level is 83 mIU/L. What does this indicate?

  • The patient's thyroid gland is producing too little thyroid hormone. (correct)
  • The patient's thyroid gland is functioning normally.
  • The patient's thyroid gland is producing too much thyroid hormone.
  • The patient's TSH level is within the normal range.

    • Which of the following best describes the mechanism of drug interactions that affect absorption?

  • Induction of drug-metabolizing enzymes.
  • Direct inhibition of enzyme activity.
  • Alterations in solubility or chelation. (correct)
  • Competition for protein binding sites.

    • Drug interactions that involve protein binding primarily affect which aspect of drug action?

  • Distribution. (correct)
  • Metabolism.
  • Absorption.
  • Excretion.

    • What is the primary site of action for CYP450 enzymes?

    <p>Liver and Intestines. (D)</p> Signup and view all the answers

    What can happen when drugs compete for the same CYP450 enzyme subgroup?

    <p>Increased metabolism of one drug and decreased metabolism of the other. (A)</p> Signup and view all the answers

    What type of drug interaction is described in the text?

    <p>Pharmacokinetic (B)</p> Signup and view all the answers

    Which of the following pharmacokinetic parameters can be affected by drug interactions?

    <p>All of the above (D)</p> Signup and view all the answers

    What is the primary goal of managing pharmacokinetic interactions?

    <p>To keep the plasma drug concentration of the affected drug relatively unchanged (D)</p> Signup and view all the answers

    How can increased absorption interactions be influenced?

    <p>All of the above (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of P-glycoprotein (P-gp)?

    <p>P-gp inducers can increase the concentration of P-gp substrates. (A)</p> Signup and view all the answers

    What is an example of a medication whose absorption is affected by antacids?

    <p>Levothyroxine (A)</p> Signup and view all the answers

    What is the primary role of Organic Anion Transporting Polypeptides (OAT-P) in drug metabolism?

    <p>They mediate the uptake of medications and endogenous compounds by the liver. (A)</p> Signup and view all the answers

    Which type of drug interaction primarily leads to increased drug bioavailability?

    <p>Enzyme inhibition (D)</p> Signup and view all the answers

    Why might spacing dose administration be a viable way of managing absorption interactions?

    <p>To minimize the effect of the interacting drug on absorption (C)</p> Signup and view all the answers

    What is the potential impact of long-term antibiotic use on drug absorption?

    <p>Decreased absorption of other medications (A)</p> Signup and view all the answers

    What is the primary consequence of enzyme induction in drug metabolism?

    <p>Decreased drug levels in the body (D)</p> Signup and view all the answers

    Which of the following statements is TRUE about the duration of drug interaction effects?

    <p>Both enzyme inhibition and induction effects last until the drug is eliminated from the body. (D)</p> Signup and view all the answers

    In the patient case presented, what drug interaction is potentially occurring?

    <p>Calcium carbonate decreases the absorption of levothyroxine (D)</p> Signup and view all the answers

    What two effects are listed for drug interactions?

    <p>Decrease drug metabolism and increase concentration (B), Increase drug metabolism and decrease concentration (C)</p> Signup and view all the answers

    Which of these factors is NOT mentioned as being important to consider when faced with a potential drug interaction?

    <p>Frequency of the interaction (C)</p> Signup and view all the answers

    What is the object of the drug interaction in the case presented?

    <p>Simvastatin (D)</p> Signup and view all the answers

    Based on the provided information, what type of drug interaction is likely occurring in the case presented?

    <p>Inhibition (D)</p> Signup and view all the answers

    How soon after the last dose of an inhibitor drug are concentrations likely to return to normal?

    <p>3-4 half-lives (B)</p> Signup and view all the answers

    A patient is taking simvastatin and is prescribed clarithromycin. What is the potential interaction?

    <p>Clarithromycin slows down the metabolism of simvastatin. (B)</p> Signup and view all the answers

    What is the recommended course of action when a patient is taking simvastatin and is prescribed clarithromycin?

    <p>Consider an alternative antibiotic or statin. (D)</p> Signup and view all the answers

    A patient is taking sertraline and starts taking St. John's Wort. This interaction is classified as:

    <p>An antagonistic interaction. (B)</p> Signup and view all the answers

    What is the primary concern regarding the interaction between St. John's Wort and sertraline?

    <p>Decreased effectiveness of sertraline. (C)</p> Signup and view all the answers

    What is the main factor driving the interaction between clarithromycin and simvastatin?

    <p>Both medications are metabolized by the same enzyme. (C)</p> Signup and view all the answers

    Which of these is a direct example of a drug interaction that is described in the provided content?

    <p>Clarithromycin and simvastatin. (C)</p> Signup and view all the answers

    Which of the following is a common concern associated with drug interactions mediated by CYP450 enzymes?

    <p>Increased risk of drug toxicity. (B)</p> Signup and view all the answers

    Which of the following best describes the interaction between clarithromycin and simvastatin, based on the information provided?

    <p>Clarithromycin inhibits the metabolism of simvastatin. (C)</p> Signup and view all the answers

    The patient is taking simvastatin. What potential food-drug interaction should be considered when discussing red yeast rice with him?

    <p>Red yeast rice is a known inhibitor of CYP3A4, which is the primary enzyme responsible for metabolizing simvastatin. (D)</p> Signup and view all the answers

    What is a key principle in patient counseling related to natural product use?

    <p>Actively inquire about OTC and herbal supplements used by patients during each visit. (B)</p> Signup and view all the answers

    Which of the following natural product interactions has the most prolonged effect?

    <p>Grapefruit juice increasing the concentration of certain drugs. (A)</p> Signup and view all the answers

    Which category of patients is particularly vulnerable to adverse effects from natural products?

    <p>Patients with chronic illnesses and polypharmacy. (B)</p> Signup and view all the answers

    Which of the following enzymes is most commonly inhibited by grapefruit juice?

    <p>CYP3A4 (D)</p> Signup and view all the answers

    What does the text refer to when it mentions "food-drug interactions"?

    <p>The impact of food on the absorption, metabolism, and excretion of drugs. (B)</p> Signup and view all the answers

    What is the key takeaway from the patient's case scenario regarding red yeast rice and simvastatin?

    <p>Red yeast rice may not be a suitable supplement for patients taking simvastatin due to potential drug interactions. (B)</p> Signup and view all the answers

    Study Notes

    Basics of Drug Interactions

    • Drug interactions can cause significant harm.
    • 48.6% of people using at least one prescription drug in the past 30 days.
    • 24.0% of people using three or more prescription drugs in the past 30 days.
    • 12.8% of people using five or more prescription drugs in the past 30 days.
    • 15% risk of interaction for two medications.
    • 40% risk of interaction for five medications.
    • 80% risk of interaction for seven or more medications.

    Learning Objectives

    • Describe the types of drug interactions.
    • Recognize substrates, inhibitors, and inducers involved in interactions.
    • Identify tools that can assist in identifying and managing drug interactions.
    • Develop strategies to manage different types of drug interactions.

    Drug-Drug Interactions

    • A drug can be changed by the presence of another drug, herbal supplement, food, or beverage.
    • Drug-drug interactions can affect either pharmacodynamics or pharmacokinetics.

    Pharmacodynamics Interactions

    • Interaction between either shared or competing mechanisms of drug action.

    Agonist vs Antagonist

    • Agonist: activation
    • Antagonist: inhibition

    Pharmacodynamic Interactions Examples

    • Warfarin (inhibits vitamin K) and Vitamin K: decreased effect of both drugs.
    • Warfarin (anticoagulant) and Apixaban (anticoagulant): increased bleed risk.
    • Ondansetron and Haloperidol: increased risk of QT prolongation/Torsades de pointes.
    • NSAIDS and ACE-I/ARBs: risk of acute kidney injury.
    • Midodrine (alpha-1 agonist) and Terazosin (alpha-1 antagonist): potential consequences of orthostatic hypotension or BPH worsening.

    Pharmacokinetic Interactions

    • Interactions where one or both drug's pharmacokinetic parameters are altered by the presence of the other drug.
    • Interactions interfere with ADME: absorption, distribution, metabolism, and excretion/elimination.

    Absorption Interactions

    • Increased absorption interactions can be influenced by pH effects. Levothyroxine absorption is decreased by antacids. Spacing doses.
    • Altered bacterial flora: Long-term antibiotics may affect absorption.
    • Altered gastrointestinal tract motility: Some medications increase peristalsis, decreasing absorption time.

    Patient Case #1

    • 52-year-old woman taking levothyroxine 100 mcg daily and calcium carbonate 600 mg twice a day.
    • High TSH level (83 mIU/L) despite consistent levothyroxine.
    • Calcium may decrease levothyroxine absorption; separate doses.

    Patient Case #2

    • 40-year-old woman taking lisinopril, hydrochlorothiazide, and simvastatin.
    • Considering prescribing Biaxin (clarithromycin).
    • Clarithromycin and simvastatin, an interaction is possible (avoid)

    Patient Case #3

    • Patients using oral hormonal contraceptives should switch to a non-oral or barrier method for 4 weeks after starting or escalating tirzepatide.
    • Tirzepatide may delay gastric emptying, reducing oral contraceptive absorption.

    Patient Case #4

    • 32-year-old woman taking sertraline.
    • Starting St John's Wort.
    • Strongly discourage this combination; serotonin syndrome risk. St John's Wort could increase or decrease the effectiveness of the serotoneric agents.

    What if our patient is on a natural supplement not listed on LexiDrug?

    • Many areas of natural supplements are not well-defined (mechanism of action, disease interactions, drug interactions, adverse effects).
    • High-risk patients include elderly, infants, pregnant or lactating women, or those on polypharmacy.
    • Lexi-Drug database
    • Natural Medicines Database
    • Liverpool Drug Interaction Checker (for HIV or COVID medications)
    • Personal team pharmacist

    Key concepts

    • Pharmacodynamics, pharmacokinetics, and bioavailability interactions.
    • Dose spacing, induction, and inhibition.
    • Drug interactions with food and supplements.
    • Tools for checking drug interactions (Lexi-Drug database, Liverpool checker).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Drug Interactions PA_Ray_2025 HANDOUT PDF

    Description

    This quiz focuses on the essential concepts of drug interactions, including the types, risks, and management strategies. Learn to identify substrates, inhibitors, and inducers involved in these interactions, as well as the significance of pharmacodynamics and pharmacokinetics. Test your knowledge on how to effectively manage drug-drug interactions to improve patient safety and health outcomes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser