Pharm Week 2
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Questions and Answers

Why was propranolol discontinued?

  • Severe side effects during treatment
  • Ineffective in treating anxiety
  • It blocks both beta 1 and beta 2 receptors (correct)
  • Development of a better alternative medication

    • Why is Verapamil considered a better treatment option than Propranolol?

  • Treats hypertension by blocking calcium channels in smooth muscle (correct)
  • Treats the hypertension and does not block the effects of epinephrine (and similar drugs) on the relaxation of smooth muscle in the lungs (which is a beta receptor mediated drug action) (correct)
  • It doesn't interact with other medications.
  • It is less costly.

    • What is a receptor?

  • A type of neurotransmitter
  • Component of a cell to which a drug binds and initiates a chain of biochemical events leading to the drug’s observed effects. (correct)
  • A type of enzyme
  • A structural component of a cell

    • What is a ligand?

    <p>A molecule that binds to a receptor.</p> Signup and view all the answers

    What do receptors determine in the context of pharmacology?

    <p>The quantitative relation between drug dose and pharmacological effect</p> Signup and view all the answers

    What is a drug response proportional to?

    <p>The number of drug-receptor complexes that form</p> Signup and view all the answers

    What do receptors provide?

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

    What do receptors mediate the actions of?

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

    What brain compound is the natural form of THC?

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

    Which of the following are non-competitive antagonists

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

    Which of the following are competitive antagonists?

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

    What two drugs are examples of chemical antagonists?

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

    What are two examples of physiological antagonists?

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

    Match each receptor to its definition

    <p>Intracellular receptor = Lipid soluble drug passes directly through the cell membrane and bind. DNA regulation is often the ultimate result. Transmembrane receptor (Cytokine) = Ligand binds on the outside surface of the cell membrane and an intracellular enzyme is activated Transmembrane kinase = Ligand binds but a specific intracellular protein kinase is activated. Ligand gated Receptor = Ligand binds and opens an ion channel</p> Signup and view all the answers

    Match each receptor to its definition

    <h1>Voltage Gated Channel = Ligand binds and opens a voltage gated ion channel.Electrical signal opens the channel G-protein receptor = 40% of all drugs act through this type of receptor</h1> <p>=</p> Signup and view all the answers

    Match each receptor type to a receptor example that corresponds to it

    <p>Gene activated intracellular = estrogen receptor Transmembrane kinase = insulin receptor Ligand Gated Ion Channel = voltage gated Na+ channel G-Protein Second Messenger = histamine H2</p> Signup and view all the answers

    Match each receptor type to a receptor example that corresponds to it

    <h1>Cytokine Receptors = WBC IL2 receptor Enzymes = Ach receptor Membrane Carrier Enzymes = Na+/K+ pump;NE re-uptake pump; 5HT re-uptake pump</h1> Signup and view all the answers

    Which of the following is an agonist for a gene activated intracellular receptor?

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

    Which of the following is an antagonist for a gene-activated intracellular receptor?

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

    Which of the following is an example of a transmembrane kinase agonist?

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

    Which of the following is an example of a ligand gated ion channel antagonist?

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

    Which of the following is a G-protein second messenger antagonist?

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

    Which of the following is an example of an enzyme receptor antagonist?

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

    Which of the following are membrane carrier enzyme channel antagonists?

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

    What is coupling in reference to receptors in pharmacology?

    <p>Transduction of drug binding to the receptor into a biochemical response.</p> Signup and view all the answers

    What is an effector in terms of pharmacology?

    <p>Component that transduces the binding event</p> Signup and view all the answers

    What is EC50?

    <p>The concentration of a drug that gives half of the maximum effect</p> Signup and view all the answers

    What does Kd represent in pharmacology?

    <p>Concentration of a drug that binds 50% of the available receptors</p> Signup and view all the answers

    What is representative of a spare receptor?

    <p>Kd &gt; EC50</p> Signup and view all the answers

    What is the significance of a spare receptor mean?

    <p>A max response can be achieved with a low drug concentration. Low is good</p> Signup and view all the answers

    What is an example of a partial agonist?

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

    Which opioid is buprenorphine a safer analgesic option to?

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

    Inverse agonists do not cause biological alteration directly; antagonists do

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

    What is an example of an antagonist that binds to opioid receptors and causes no biological response?

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

    What is the active receptor conformation in pharmacology?

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

    Which receptor conformation do natural endogenous ligands bind to?

    <p>Active conformation</p> Signup and view all the answers

    Are drugs that have low intrinsic efficacy full agonists or partial agonists?

    <p>partial agonists</p> Signup and view all the answers

    Which of the following receptors has the characteristic of binding to the Ra form of the receptor and shifts the receptor pool to almost all the Ra form?

    <p>Full agonist</p> Signup and view all the answers

    Which receptor has the following characteristic: drugs bind to the receptor and keep the pool at the same Ra and Ri proportions, maintaining the 'natural' balance?

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

    Which receptor has the following characteristic: Drugs bind to the Ri form of the receptor and drive the pool toward the Ri form?

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

    Which type of antagonists has the following characteristic: Compete for the same site that the agonist wants. If the antagonist wins, there is no biological response.

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

    What is an example of an irreversible antagonist?

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

    What stimulates intracellular enzyme guanylyl cyclase which produces the second messenger cGMP?

    <p>Nitric oxide (NO)</p> Signup and view all the answers

    What binds to intracellular DNA regulator proteins which alter and allow protein transcription to initiate?

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

    What is receptor desensitization?

    <p>The reduction in response to a stimulus after repeated exposure.</p> Signup and view all the answers

    What is receptor downregulation?

    <p>The decrease in receptor number or sensitivity after prolonged exposure to an agonist.</p> Signup and view all the answers

    Which receptor increases heart rate?

    <p>Beta-1 adrenergic receptor</p> Signup and view all the answers

    Which receptor is primarily responsible for vasoconstriction?

    <p>Alpha-1 adrenergic receptor</p> Signup and view all the answers

    Which receptor opens potassium channels?

    <p>Alpha 2 receptors</p> Signup and view all the answers

    What is the therapeutic index of a drug?

    <p>The measure of a drug's toxicity</p> Signup and view all the answers

    What is the therapeutic range of theophylline?

    <p>10-20 mcg/mL</p> Signup and view all the answers

    What is the therapeutic range of digoxin?

    <p>0.8 to 1.2 ng/mL</p> Signup and view all the answers

    Study Notes

    Propranolol and Verapamil

    • Propranolol has been discontinued in some cases due to its side effects and less effective management of certain conditions.
    • Verapamil is often favored over propranolol as it offers better efficacy in managing certain cardiovascular conditions, such as hypertension and angina.

    Receptors and Ligands

    • A receptor is a protein molecule that receives and transmits signals in response to ligands.
    • A ligand is a molecule that specifically binds to a receptor to initiate a biological response.
    • Receptors determine the interaction of drugs with biological systems, affecting therapeutic outcomes.
    • Drug response is proportional to the concentration of the drug that binds to the receptor.

    Functions and Mechanisms

    • Receptors provide a specific binding site for ligands, leading to various cellular responses.
    • They mediate the actions of neurotransmitters, hormones, and various drugs.
    • The natural form of THC in the brain is anandamide, which plays a role in signaling.

    Antagonists and Agonists

    • Non-competitive antagonists bind to receptors without preventing ligand binding, effectively inhibiting receptor activity.
    • Competitive antagonists compete directly with agonists for receptor binding sites.
    • Chemical antagonists are drugs that neutralize the effects of another substance; examples include naloxone and flumazenil.
    • Physiological antagonists counteract the effects of an agonist through different pathways, e.g., glucagon vs. insulin.

    Receptor Classifications

    • Agonists for gene-activated intracellular receptors activate these receptors to elicit a response.
    • Antagonists inhibit the action of gene-activated intracellular receptors.
    • Ligand-gated ion channel antagonists prevent the opening of ion channels, affecting ionic currents across membranes.

    Pharmacology Concepts

    • Coupling refers to the relationship between receptor activation and subsequent intracellular signaling, involving effectors.
    • An effector is a molecule that mediates the physiological effects initiated by receptor activation.
    • EC50 is the concentration of a drug that produces 50% of its maximum effect.
    • Kd represents the dissociation constant, indicating the affinity between a ligand and its receptor.

    Spare Receptors and Agonists

    • Spare receptors are unoccupied receptors that contribute to the maximum effect even when a small fraction of receptors are activated.
    • A partial agonist is a drug that activates a receptor but produces a lower response than a full agonist.
    • Buprenorphine is a safer analgesic option compared to traditional opioids like morphine.

    Antagonist Characteristics

    • An antagonist that binds to opioid receptors but causes no biological response is naloxone.
    • The active receptor conformation is the state that allows for ligand binding.
    • Full agonists have high intrinsic efficacy, while drugs with low intrinsic efficacy are classified as partial agonists.

    Receptor Forms and Binding

    • Receptors can exist in active (Ra) and inactive (Ri) conformations, influencing drug effects.
    • Agonists typically stabilize the Ra form, while certain drugs might maintain a natural balance between Ra and Ri.
    • The Ri form is stabilized by inverse agonists, producing opposite effects to those of full agonists.

    Antagonist Types

    • Competitive antagonists share the same binding site as agonists; if they occupy the site, they block biological responses.
    • An example of an irreversible antagonist is phenoxybenzamine, which permanently binds to receptors.

    Intracellular Signaling

    • Nitric oxide stimulates intracellular enzyme guanylyl cyclase, producing the second messenger cGMP.
    • Certain drugs bind to intracellular DNA regulator proteins to initiate transcription and alter protein synthesis.

    Receptor Regulation

    • Receptor desensitization occurs when receptors become less responsive to ligands after prolonged exposure.
    • Receptor downregulation involves the reduction in receptor number on the cell surface, often due to overactivation.

    Specific Receptor Functions

    • Beta-1 adrenergic receptors increase heart rate, while alpha-1 adrenergic receptors are primarily responsible for vasoconstriction.
    • Potassium channels are opened by certain receptors to regulate neuronal excitability.

    Therapeutic Considerations

    • The therapeutic index is a measure of drug safety, calculated as the ratio of the toxic dose to the effective dose.
    • The therapeutic range for theophylline is narrow, usually around 10-20 mg/L.
    • The therapeutic range for digoxin varies, typically 0.5-2 ng/mL, to ensure effectiveness while avoiding toxicity.

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    Description

    Test your knowledge about the reasons behind the discontinuation of propranolol. This quiz covers various aspects of the drug's history, usage, and the factors leading to its cessation. Learn about its implications in the medical field.

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