Pharmacology: Potency and Drug Dosage
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Questions and Answers

What is the term for the process by which the number of receptors in a cell is increased in response to repeated drug treatment?

  • Phosphorylation
  • Desensitisation
  • Up-regulation (correct)
  • Downregulation

    • What is the term for the rapid development of tolerance to a drug?

  • Downregulation
  • Tachyphylaxis (correct)
  • Tolerance
  • Desensitisation

    • What is the term for the process by which an agonist produces less effect the longer it remains in contact with the receptor?

  • Downregulation
  • Desensitisation (correct)
  • Phosphorylation
  • Up-regulation

    • What is the term for the study of the relationship between the dose of a drug and its effect?

    <p>Pharmacodynamics</p> Signup and view all the answers

    What is the term for the process by which the effect of a drug is reduced due to repeated administration?

    <p>Tolerance</p> Signup and view all the answers

    What is the term for the process by which receptors are removed from the surface of the cell?

    <p>Internalisation</p> Signup and view all the answers

    What is the term for the study of how the body affects the drug, as opposed to how the drug affects the body?

    <p>Pharmacokinetics</p> Signup and view all the answers

    What is the term for the process by which the number of receptors in a cell is reduced in response to repeated drug treatment?

    <p>Downregulation</p> Signup and view all the answers

    What determines the potency of a drug?

    <p>The strength of binding of a drug to a receptor</p> Signup and view all the answers

    Which type of antagonism is reversible?

    <p>Competitive antagonism</p> Signup and view all the answers

    What is the measure of the effectiveness of a drug in producing a maximum response?

    <p>Efficacy</p> Signup and view all the answers

    What is the dose-response curve shifted to when there are spare receptors?

    <p>To the left of the KD</p> Signup and view all the answers

    Which of the following is a characteristic of an agonist?

    <p>It has high efficacy</p> Signup and view all the answers

    What is the purpose of dose-response measurements?

    <p>To determine the accurate dosing needed when new drugs are formulated</p> Signup and view all the answers

    What is the definition of a drug?

    <p>An agent that interacts with specific target molecules in the body and produces a physiological effect</p> Signup and view all the answers

    What is the result of increasing doses of an agonist on a receptor?

    <p>Increasing response until a maximum response is reached</p> Signup and view all the answers

    What is pharmacodynamics?

    <p>The mechanism by which drugs exert their effect on the body to produce a therapeutic action</p> Signup and view all the answers

    What is the relationship between KD and affinity?

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

    What is the term for the attraction of a drug for binding to a receptor?

    <p>Affinity</p> Signup and view all the answers

    What type of receptors are involved in fast neurotransmission?

    <p>Ligand-gated ion channels</p> Signup and view all the answers

    What is the term for a ligand that produces a response when it binds to a receptor?

    <p>Agonist</p> Signup and view all the answers

    What determines the maximum response that a drug can produce?

    <p>Efficacy</p> Signup and view all the answers

    What is the term for the ability of a drug to distinguish between different receptors?

    <p>Selectivity</p> Signup and view all the answers

    What is the term for a substance that can cause birth defects?

    <p>Teratogen</p> Signup and view all the answers

    Study Notes

    Pharmacodynamics

    Potency and Efficacy

    • Potency: the measure of the drug dosage needed to produce a particular therapeutic effect, determined by the strength of binding of a drug to a receptor or the receptor affinity for the drug.
    • Efficacy: the measure of the effectiveness of a drug in producing a maximum response.
    • Full agonists have high efficacy, while antagonists have no efficacy.

    Dose-Response Measurement

    • Used to determine accurate dosing needed when new drugs are formulated.
    • Cannot use these measurements to calculate affinity only dosing.
    • Agonists bind to receptors causing contractions, which are plotted, and increasing doses lead to increasing responses until two doses have an equal response.

    Drug Antagonism

    • Competitive (or surmountable) Antagonism: agonists and antagonists compete for the same receptor sites, and the maximal effect remains unchanged.
    • Non-Competitive (or irreversible) Antagonism.
    • Physiological Antagonism.

    Molecular Aspects of Drug Action

    • The number of receptors in a cell is not static but dynamic, with a high turnover of receptors as they are continuously removed or replaced.
    • Repeated drug treatment may up-regulate or downregulate the receptor numbers.

    Tolerance, Desensitisation, and Tachyphylaxis

    • Tolerance: the same dose of drug, on repeated administration, produces less effect.
    • Desensitisation: less effect is produced the longer the agonist remains in contact with the receptor.
    • Tachyphylaxis: tolerance that develops very rapidly.
    • Causes of desensitisation/tachyphylaxis/tolerance: change in receptors (phosphorylation), downregulation of receptors (internalisation/reduced expression), depletion of mediator, and increased metabolic breakdown.

    Pharmacology and Lifestyle

    • Food as drugs – nutraceuticals, and food-drug interactions.
    • Exercise: effect of exercise on drugs (pharmacokinetics and pharmacodynamics), activation or induction of antioxidant systems, and effect of drugs on exercise.

    The Role of Pharmacodynamics in Pharmacology

    • Provides information regarding dose/dosage regimen vs response.
    • Factors affecting pharmacodynamics, together with pharmacokinetics, are considered when a dose is individualised for special populations such as the elderly.
    • Useful tool for introducing new indications, new dosages, or new treatment populations, contributing to valuable information for drug development.

    Introduction to Pharmacodynamics

    • Pharmacodynamics is the mechanism by which drugs exert their effect on the body in order for a therapeutic action to occur.
    • Pharmacodynamics encompasses drug-receptor interactions and the general principle of drug action.
    • Pharmacokinetics is what the body does to the drug.

    Types of Drugs

    • Drugs with activity at high concentrations: have structural specificity and cause physical change (general anaesthetics).
    • Drugs acting at low concentrations: act by chemical rather than physical interaction (Isoprenaline).

    Receptors

    • The site at which a ligand (agonist) can attach.
    • Ligands (drugs) may be neurotransmitters, hormones, or local factors.
    • Activation of receptors by a ligand or agonist produces a response (effect).
    • Affinity: the attraction of a drug for binding.
    • Selectivity: the ability of a drug to bind to a specific receptor.
    • Types of receptors: ligand-gated ion channels (fast neurotransmitters) and G-protein coupled receptors (slow neurotransmitters).

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    Description

    Learn about the concept of potency in pharmacology, how it affects drug dosage, and the importance of receptor affinity and ED50.

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