Pharmacodynamics 1 Lecture Notes
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Questions and Answers

What is one possible outcome of increasing the dose after reaching maximal efficacy?

  • The side effects will become less severe.
  • The response will increase significantly.
  • The response will remain the same. (correct)
  • The body will adapt to the increased dosage.

    • What may occur if a dose is increased beyond the maximal efficacy?

  • Enhanced therapeutic effects.
  • Improved cellular response.
  • Increased risk of toxicity. (correct)
  • Decreased likelihood of side effects.

    • Increasing the dose after maximal efficacy is reached could result in which of the following?

  • Increased absorption of the drug.
  • Immediate withdrawal symptoms.
  • Heightened immune response.
  • Cellular exhaustion. (correct)

    • When maximal efficacy has been achieved, what happens to the effectiveness of subsequent doses?

    <p>Effectiveness may remain unchanged.</p> Signup and view all the answers

    What should be avoided to ensure optimal study conditions after reaching maximal efficacy?

    <p>Increasing the dose drastically.</p> Signup and view all the answers

    What is a common consequence of increasing the dose of a drug?

    <p>It may lead to side effects due to targeting other proteins</p> Signup and view all the answers

    What is true about drug specificity?

    <p>No drugs are completely specific and may target other proteins</p> Signup and view all the answers

    What is the relationship between side effects and adverse effects?

    <p>All adverse effects are side effects</p> Signup and view all the answers

    What term is used to describe the effects of a drug that are not its principal target?

    <p>Side effects</p> Signup and view all the answers

    How do side effects arise when using medications?

    <p>From increasing the dose beyond the therapeutic level</p> Signup and view all the answers

    What does a higher association constant (Ka) generally indicate about a ligand's affinity for a receptor?

    <p>Higher affinity</p> Signup and view all the answers

    What is the significance of the dissociation constant (Kd) in receptor-ligand interactions?

    <p>It reflects the rate at which the ligand dissociates from the receptor</p> Signup and view all the answers

    If a drug has an association constant of 140, what can be inferred about the ligand-gated ion channel?

    <p>It shows significant receptor-ligand interaction.</p> Signup and view all the answers

    In ligand-gated ion channels, how is the α parameter related to the drug's association and dissociation constants?

    <p>α is directly proportional to Ka and inversely proportional to Kd.</p> Signup and view all the answers

    What would a very high Kd value imply about the ligand-gated ion channel's functionality?

    <p>It suggests that the ligand can easily dissociate from the channel.</p> Signup and view all the answers

    What should be done if a patient does not respond to the initial medication dose?

    <p>Increase the dosage until maximal efficacy is reached</p> Signup and view all the answers

    What is indicated if a patient still does not respond after reaching the drug's maximum efficacy?

    <p>Change to another drug</p> Signup and view all the answers

    What is the role of E-max in medication administration?

    <p>It signifies the point of maximal drug effect</p> Signup and view all the answers

    If a patient is unresponsive to treatment, what is NOT an appropriate action?

    <p>Maintain the same dosage without changes</p> Signup and view all the answers

    Which statement about adjusting medication dosage is FALSE?

    <p>Change of drug is necessary only if there are adverse effects.</p> Signup and view all the answers

    What does a higher curve indicate regarding the efficacy of a drug?

    <p>It is more efficacious.</p> Signup and view all the answers

    How can the efficacy of a drug be assessed?

    <p>By observing the height of the efficacy curve.</p> Signup and view all the answers

    If a drug's efficacy curve is low, what can be inferred about the drug?

    <p>It is less efficacious.</p> Signup and view all the answers

    Why is it important to evaluate the height of the efficacy curve?

    <p>To assess how effective the drug is.</p> Signup and view all the answers

    In the context of drug efficacy, what does a lower curve compared to a higher one suggest?

    <p>The drug is likely ineffective.</p> Signup and view all the answers

    What does the ED50 represent in pharmacology?

    <p>The dose that results in therapeutic effects in 50% of the patients</p> Signup and view all the answers

    How is the therapeutic index calculated?

    <p>LD50 divided by ED50</p> Signup and view all the answers

    If Drug 1 has a therapeutic index of 10 and Drug 2 has a therapeutic index of 5, which drug has a wider safety margin?

    <p>Drug 1</p> Signup and view all the answers

    Which of the following statements is true regarding LD50 and ED50?

    <p>LD50 is always higher than ED50 for safe medications.</p> Signup and view all the answers

    What can be inferred about Drug 1 and Drug 2 if they have the same ED50 but different LD50 values?

    <p>Drug 1 has a wider safety margin than Drug 2.</p> Signup and view all the answers

    Study Notes

    Pharmacodynamics 1 Lecture Notes

    • Pharmacodynamics is the study of what a drug does to the body.
    • It describes the pharmacological actions of a drug.
    • The effect of the drug on the human body is called pharmacodynamics
    • The effect of the human body on a drug is called pharmacokinetics.
    • Drugs modify existing functions, possibly increasing or decreasing them.
    • Drugs must target specific sites within cells to work.
    • Drug targets are proteins, including enzymes, carrier proteins, ion channels, and receptors.
    • Ligand specificity is important for drug action; drugs bind to specific molecules in cells with high precision.
    • Drugs are not completely specific in their actions. Increasing the dose might affect unintended targets, leading to side effects.
    • Side effects are unavoidable, especially with higher doses.
    • There are two main types of drug interactions:
      • Agonists: bind and activate receptors (may be full or partial).
      • Antagonists: bind to receptors but do not activate them (zero efficacy).
    • Affinity is the ability of a drug to bind to a receptor.
    • Efficacy is the ability of the drug-receptor complex to produce a cellular response.
    • A dose-response curve shows the relationship between drug dose and response.
    • The curve rises until maximum efficacy is reached
    • Threshold dose: the dose below which no effect is observed
    • Efficacy is assessed by measuring the height of the dose-response curve
    • Potency is determined by the dose needed to achieve a specific effect (often 50% of maximum effect, ED50).
    • A higher potency means a lower dose is needed.
    • Therapeutic index is the ratio of the lethal dose (LD50) to the effective dose (ED50) for a drug. A higher therapeutic index indicates a safer drug.
    • Competitive antagonists shift the agonist's dose-response curve to the right without decreasing maximal response.
    • Irreversible antagonists shift the curve both to the right and down, decreasing maximal efficacy.
    • Drug action refers to the initial molecular events after drug binding.
    • Drug effects refer to the observable changes in physiological function.
    • Drug actions cannot be measured, whereas effects can be observed and measured.
    • A drug can have affinity but not efficacy.

    Quiz Questions

    • A drug has a Ka of 140 and a Kd of 2. Calculate its affinity.
    • How many alpha subunits are present in ligand-gated ion channels?

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    Pharmacodynamics I (2024-2025) PDF

    Description

    Explore the fundamental concepts of pharmacodynamics, which focuses on how drugs affect the body. This quiz covers drug actions, target sites, ligand specificity, and the nature of drug interactions, including agonists and antagonists. Enhance your understanding of pharmacological effects and side effects in drug therapy.

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