Pharmacology Introduction: Pharmacokinetics and Pharmacodynamics
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Questions and Answers

What type of antagonism occurs when two drugs bind to different receptors, stimulating opposite functions?

  • Competitive antagonism
  • Physiologic antagonism (correct)
  • Chemical antagonism
  • Noncompetitive antagonism

    • What determines the duration of action of an irreversible antagonist?

  • Speed at which new receptors are produced (correct)
  • Diffusion of the drug away from the site of action
  • Metabolism of the agent
  • The half-life of the agent

    • What is the term for the combined effect of two drugs being greater than the sum of their individual effects?

  • Potentiation
  • Addition
  • Synergism (correct)
  • Antagonism

    • What is the result of continued stimulation of receptors with agonists?

    <p>B &amp; C</p> Signup and view all the answers

    What is the therapeutic index?

    <p>The range between the concentration that produces a desired effect and one that produces a toxic effect</p> Signup and view all the answers

    What is the primary factor that influences the ability of a drug to cross cell membranes?

    <p>The concentration gradient</p> Signup and view all the answers

    What happens to basic drugs when they enter a more basic environment than their pKa?

    <p>They become more nonionized</p> Signup and view all the answers

    What is the term for the enhancement of the action of one drug by another that has no detectable action of its own?

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

    What happens to acidic drugs when they enter a more basic environment than their pKa?

    <p>They become more ionized</p> Signup and view all the answers

    What is the term for the phenomenon where the action of one drug is opposed by another?

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

    What is the primary factor that determines the degree of ionization of an agent as it crosses a membrane?

    <p>pKa of the agent</p> Signup and view all the answers

    What is the term for the uptake of a drug across tissues and its movement into the bloodstream?

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

    According to Fick's law, what is the rate of diffusion across a specific membrane dependent on?

    <p>Concentration gradient, area of membrane, solubility of drug, thickness of membrane, and molecular weight of drug</p> Signup and view all the answers

    What is the fraction of the administered drug that actually reaches the systemic circulation?

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

    What happens to Lidocaine when it crosses the placenta?

    <p>It becomes more ionized</p> Signup and view all the answers

    What is the term for a drug becoming trapped in a specific area because of its increased ionization?

    <p>Ion trapping</p> Signup and view all the answers

    What is pharmacokinetics concerned with?

    <p>What the body does to the drug</p> Signup and view all the answers

    What is the term for the ability of a drug to produce a desired response?

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

    What is the term for the amount of drug needed to produce an effect in 50% of the population?

    <p>ED50</p> Signup and view all the answers

    What type of receptor binding is irreversible?

    <p>Covalent bonding</p> Signup and view all the answers

    What is the term for the dosage range that provides safe therapy?

    <p>Therapeutic window</p> Signup and view all the answers

    What is the term for a drug that binds to a receptor and blocks its function?

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

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

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

    What is the term for the rapid decrease in response to a given dose of a drug?

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

    What is the most common site of receptor binding?

    <p>Cell membrane</p> Signup and view all the answers

    What can be assumed if a drug name contains 'sodium', 'calcium', or 'magnesium'?

    <p>The drug is the salt form of a weak acid</p> Signup and view all the answers

    What type of ion does a weak base typically unite with?

    <p>Negatively charged ions</p> Signup and view all the answers

    If a drug name contains 'chloride' or 'sulfate', what can be assumed about the drug?

    <p>The drug is the salt form of a weak base</p> Signup and view all the answers

    What is the percentage of the ionized form of a weak acid with a pKa of 4 at a moving into a solution with a pH of 11?

    <p>99-100%</p> Signup and view all the answers

    What is the percentage of the ionized form of a weak acid with a pKa of 10 entering a solution with a pH of 9.5?

    <p>75%</p> Signup and view all the answers

    A basic drug with a pKa of 7.4 is given IV. What is the percentage of the drug in the ionized form?

    <p>50%</p> Signup and view all the answers

    What is the relationship between the pKa of a drug and the pH of the environment in which it is administered?

    <p>The pKa is equal to the pH when the drug is 50% ionized and 50% unionized</p> Signup and view all the answers

    What is the primary route that a drug takes after being absorbed from the GI tract?

    <p>Portal venous system and then systemic circulation</p> Signup and view all the answers

    What happens to an oral drug that is extensively metabolized by the liver?

    <p>Little of it reaches systemic circulation</p> Signup and view all the answers

    What is the purpose of compartment models in pharmacokinetics?

    <p>To describe the distribution of a drug into the body</p> Signup and view all the answers

    What is the central compartment composed of?

    <p>The vessel rich organs/tissue</p> Signup and view all the answers

    What is the primary factor that determines the volume of distribution of a drug?

    <p>The lipid solubility of the drug</p> Signup and view all the answers

    What is the normal volume of distribution for a 70kg adult?

    <p>0.6L/kg</p> Signup and view all the answers

    What does a high volume of distribution indicate about a drug?

    <p>It is highly lipid-soluble</p> Signup and view all the answers

    What is the formula for calculating the volume of distribution of a drug?

    <p>Vd = dose / plasma concentrationT=0</p> Signup and view all the answers

    Study Notes

    Pharmacokinetics/Pharmacodynamics

    • Pharmacokinetics: What the body does to the drug (Absorption, Distribution, Metabolism, Excretion)
    • Pharmacodynamics: What the drug does to the body (MOA, effects, potency, etc.)

    Receptors

    • Protein or other substance binding to an endogenous chemical or drug (ligand)
    • Reversible vs. Irreversible binding (Aspirin irreversibly binds to platelet receptor)
    • Affinity: attraction of drug to the receptor site
    • Potency: amount of drug needed to produce effect
    • Efficacy (intrinsic activity): ability of drug to produce desired response
    • Tolerance: increased amount of drug needed to produce a given response
    • Tachyphylaxis: acute tolerance/rapid decrease in response to a given dose (e.g., nitroglycerine)

    Terminology

    • ED50: effective dose in 50% of population, ED99: effective dose in 99% of population
    • TD50: toxic dose in 50% of population, LD50: lethal dose in 50% of population
    • Ceiling Effect: dose beyond which no effect is seen, after which unwanted effects are seen
    • Therapeutic window/index: dosage range that provides safe therapy

    Receptor Binding

    • Bonds with a receptor fall into categories of strength: Van der Waals, hydrophobic, hydrogen, ionic, and covalent
    • Most common site of receptor is in the cell membrane
    • Occupancy theory: magnitude of drug's effect is proportional to number of receptors occupied
    • Square receptor concept: relationship between number of receptors bound and response is nonlinear

    Antagonism

    • Competitive antagonism: agonist and antagonist have affinity for the same receptor
    • Physiological antagonism: two agonist drugs binding to different receptors that stimulate opposite functions
    • Chemical antagonism: drugs action is blocked, but no receptor is involved

    Drug Interaction Terminology

    • Addition: combined effect of two drugs with the same mechanism produces an effect equal to that expected
    • Synergism: combined effect of two drugs is greater than the sum of individual effects
    • Potentiation: enhancement of action of one drug by another that has no detectable action of its own
    • Antagonism: action of one drug opposes another

    Up & Down Regulation

    • Continued stimulation of receptors with agonists generally results in desensitization/down-regulation
    • Continued administration of an antagonist results in up-regulation as a response to chronic blockade

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    Introduction to Pharmacology Notes PDF

    Description

    Learn about the basics of pharmacology, including pharmacokinetics, pharmacodynamics, and relevant terminology. Understand how the body interacts with drugs and how drugs affect the body.

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