Podcast
Questions and Answers
Which of the following terms describes the situation when a drug acting on one receptor increases the action of another drug acting on a different receptor?
Which of the following terms describes the situation when a drug acting on one receptor increases the action of another drug acting on a different receptor?
- Synergism (correct)
- Antagonism
- Summation (correct)
- Potentiation
A full agonist does not necessarily have the highest potency.
A full agonist does not necessarily have the highest potency.
True (A)
What is the term used to describe a rapid decrease in responsiveness to a drug after repeated administrations in quick succession?
What is the term used to describe a rapid decrease in responsiveness to a drug after repeated administrations in quick succession?
Tachyphylaxis
The Graded-Dose-Response-Curve can be used to determine the proportion of the population that therapeutically responded or developed side effects to a drug.
The Graded-Dose-Response-Curve can be used to determine the proportion of the population that therapeutically responded or developed side effects to a drug.
Match the following terms with their corresponding definitions.
Match the following terms with their corresponding definitions.
Which of the following is NOT a characteristic of a drug with a wide therapeutic window?
Which of the following is NOT a characteristic of a drug with a wide therapeutic window?
What is the term used to describe the state of a drug's effect being diminished or absent after repeated administration, and it cannot be overcome by increasing the drug concentration?
What is the term used to describe the state of a drug's effect being diminished or absent after repeated administration, and it cannot be overcome by increasing the drug concentration?
A full agonist is a drug that produces the maximal response possible for that receptor.
A full agonist is a drug that produces the maximal response possible for that receptor.
Flashcards
Efficacy
Efficacy
The ability of a drug to produce a desired effect.
Potency
Potency
The amount of drug needed to produce a specific effect.
Full Agonist
Full Agonist
A drug that produces the maximal effect.
Partial Agonist
Partial Agonist
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Potentiation
Potentiation
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Antagonism
Antagonism
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Competitive Antagonist
Competitive Antagonist
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Reversible Antagonist
Reversible Antagonist
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Irreversible Antagonist
Irreversible Antagonist
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Non-competitive Antagonist
Non-competitive Antagonist
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Synergism
Synergism
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Summation
Summation
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Graded Dose-Response Curve
Graded Dose-Response Curve
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Quantal Dose-Response Curve
Quantal Dose-Response Curve
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Dose
Dose
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Drug response
Drug response
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Study Notes
Dynamics of Drug Actions
- Efficacy vs. potency are important for drug selection.
- Comparing drug responses: Drugs acting on the same or different receptors.
- Potentiation and antagonism are important in therapy.
- Predicting drug safety is done using dose-frequency curves.
Graded Dose-Response Curve
- Used to compare drug effects.
- Comparing agonists: Some are full agonists (same efficacy as a standard), while others are partial agonists (less efficacy) and varying levels of potency
- Potentiating an agonist (shift left): increases efficacy by altering efficacy curve.
- Antagonizing an agonist (shift right): decreases efficacy.
- Competitive reversible antagonism: decreases potency but can be overcome.
- Competitive irreversible antagonism: or Non-competitive antagonism decreases efficacy that cannot be overcome.
Quantitative Comparison of Different Drugs
- Comparing drugs acting on the same receptor.
- Comparing drugs acting on different receptors. Effectiveness can vary.
- Synergism (or summation): One drug enhances the other but not in the same receptor.
Quantal Dose-Response Curve
- Used to predict drug safety:
- ED50: the dose that produces an effect in 50% of subjects
- TD50: the dose that causes a toxic effect in 50% of subjects
- Therapeutic index (TI): TD50 / ED50 A higher TI indicates a safer drug.
- Therapeutic Monitoring: Blood drug monitoring is needed when drugs have narrow therapeutic windows.
Variation in Drug Response
- Tolerance: Reduced response to a drug over time.
- Tachyphylaxis: Rapidly developing tolerance.
- Refractoriness: Loss of therapeutic efficacy.
- Resistance (in treatment): Complete loss of effectiveness to antibiotics/anticancer.
- Hypersensitivity: Increased response that can be dangerous.
- Idiosyncrasy: Abnormal response to a drug due to genetic factors.
- Hypersensitivity (allergy): An immune system reaction, to a drug.
- Dependence: Adaptive state to repeated drug use with withdrawal symptoms when stopped. (Includes Addiction)
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