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. (C)</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. (D)</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 (B)</p> Signup and view all the answers

What is true about drug specificity?

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

What is the relationship between side effects and adverse effects?

<p>All adverse effects are side effects (A), Some side effects are not considered adverse effects (D)</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 (A)</p> Signup and view all the answers

How do side effects arise when using medications?

<p>From increasing the dose beyond the therapeutic level (B)</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 (B)</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 (D)</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. (C)</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. (B)</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. (D)</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 (A)</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 (B)</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 (B)</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 (C)</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. (D)</p> Signup and view all the answers

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

<p>It is more efficacious. (A)</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. (D)</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. (C)</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. (D)</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. (B)</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 (C)</p> Signup and view all the answers

How is the therapeutic index calculated?

<p>LD50 divided by ED50 (A)</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 (D)</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. (B)</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. (A)</p> Signup and view all the answers

Flashcards

Drug side effects

Unintended effects of a drug targeting proteins other than the intended one.

Drug specificity

The ability of a drug to target only the desired protein.

Adverse effects

Unwanted and potentially harmful effects of a drug.

Side effects (vs. adverse effects)

All adverse effects are side effects, but not all side effects are adverse. Side effects can be mild or harmless.

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Association Constant (Ka)

A measure of how readily a molecule (ligand) binds to a receptor (protein).

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Dissociation Constant (Kd)

A measure of how readily a molecule (ligand) detaches from a receptor(protein).

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Ligand-Gated Ion Channel

A protein that opens or closes a channel in a cell membrane in response to a molecule (ligand) binding to it. This change allows ions to pass.

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Number of α subunits in Ligand-Gated Ion Channel?

The information provided states that there is not enough data to know how many alpha (α) subunits a Ligand-Gated Ion Channel may have.

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Drug Efficacy

How well a drug produces its intended effect.

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Higher Curve

Indicates greater efficacy of a drug

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Lower Curve

Indicates less efficacy of a drug

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Maximizing Drug Efficacy

Increasing the dose of a drug until the best possible effect is achieved.

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Drug Ineffectiveness

When a drug, even at its highest effective dosage, does not produce the desired effect.

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Switching Drugs

Changing to a different medication when the current one is not working.

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Maximal efficacy

The highest possible effect a drug can produce, no matter how high the dose.

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Dose increase beyond maximal efficacy

Increasing the drug dose beyond the maximal efficacy point will not increase the desired effect, but it may increase side effects and toxicity.

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Side effects/Toxicity

Negative effects that can occur at higher drug doses beyond the maximal efficacy point.

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Effect decrease after maximal efficacy

When the dose exceeds maximal efficacy, the effect of the drug may begin to decrease because cells involved in the desired effect can become overwhelmed or saturated.

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Therapeutic Index

A measure of a drug's safety; calculated by dividing the lethal dose (LD50) by the effective dose (ED50).

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ED50

Effective dose 50; the dose of a drug that produces a specific effect in 50% of the population.

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LD50

Lethal dose 50; the dose of a drug that kills 50% of the population.

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Drug Safety

The measure of the degree of toxicity of a particular drug.

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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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