Questions and Answers
What is the primary intention of pharmacology?
What is the term for the study of the physical, chemical, biochemical, and biological properties of drugs of natural origin?
Who isolated pure salicin from willow bark in 1828?
What is the active constituent of the Belladonna plant?
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What is the goal of modern drug development?
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What is the term for the study of the influence of single pharmacogenes on drug responses?
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What is the term for the study of the economic aspects of medicines use on a large population basis?
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Who wrote 'Pharmacologia' in 1693, describing many plants and their medicinal uses?
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What is the main focus of Pharmacogenomics?
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Which of the following is NOT a factor affecting drug absorption?
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What is the purpose of adding substituents to a drug molecule?
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What is the role of Pgp (p-glycoprotein) in the gut?
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What is the term for the reversible transfer of a drug from one location to another?
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Which of the following is a methodology used in Pharmacomicrobiomics?
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What is the purpose of Prodrugs?
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What is the term for the pH at which a drug is 50% ionised?
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Which of the following is NOT a phase of drug absorption in the GI-Tract?
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Which type of drugs can penetrate all tissues?
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What is the term for the study of effects of drugs on the body's production of hundreds or thousands of metabolites?
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What is the main function of membrane drug transporters?
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What is the volume of distribution (Vdist) a measure of?
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What is the purpose of drug metabolism?
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Where does most of xenobiotic metabolism occur?
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What is the main enzyme family involved in oxidative drug metabolism?
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What is the role of NADPH in drug metabolism?
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What happens to the logP of a drug during metabolism?
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What is a pro-drug?
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What is the significance of first-pass clearance?
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What is the role of receptors in cellular communication?
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Different cell types express the same types and densities of receptors.
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What is the function of muscarinic acetylcholine receptors in cardiac cells?
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Receptors are the cell's ______________________ elements.
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Match the following chemical agents with their corresponding receptors:
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What is the result of a chemical agent binding to a receptor?
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What is the main focus of Pharmacodynamics?
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Pharmacokinetics describes the effects of a drug on the body.
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Who said 'A drug will not work unless it is bound'?
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Most drugs exert their effects by binding to protein targets such as ______________________.
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Match the following concepts with their definitions:
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What is the primary focus of Pharmacodynamics?
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A partial agonist has higher efficacy than a full agonist.
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What is the relationship between agonist concentration and receptor occupancy?
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A surmountable receptor antagonist can be overcome by increasing the concentration of the ___________.
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Match the following terms with their definitions:
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What is the term for the analysis of the relationship between the concentration of a drug and its resulting effect?
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What type of ligand mimics the actions of endogenous ligands?
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Receptor activation requires a poor 3-D "fit" between agonist and receptor.
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What is the term for the ability of a drug to bind to only certain receptors?
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Drugs act by binding to specific ______________________ targets.
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Match the following receptors with their primary function:
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Agonist binding to receptors is usually irreversible.
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What type of forces are involved in agonist binding to receptors?
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What happens when the forces of attraction between an agonist and receptor are strong?
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The forward rate constant, k+1, measures the rate of ______________________ of the agonist to the receptor.
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Most drugs act on only one receptor.
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Study Notes
Introduction to Pharmacology
- Pharmacology is the branch of science that seeks to understand the effects of drugs on the human body with the intention of preventing, curing, or alleviating disease.
- Plants have been used as drugs throughout history, with ancient human societies aware of their drug-like actions.
Historical Origins of Pharmacology
- Dale's Pharmacologia (1693) described many plants and their medicinal uses and proposed "8 Rules" still relevant to clinical pharmacology today.
- The willow tree has been used medicinally since ancient Rome, with the isolation of salicin from its bark in 1828 and the industrial synthesis of aspirin in 1897.
- Belladonna has been used medicinally in ancient India and has been used to block cardiac vagal stimulation since 1867.
Modern Pharmacology
- The goal of modern drug development is to find drugs that "fit" target molecules, using a lock and key analogy.
- Personalised medicine, also known as pharmacogenetics, aims to use the right drug in the right patient.
- The scope of modern pharmacology includes pharmacoeconomics, pharmacogenetics, pharmacogenomics, pharmacometabolomics, and pharmacomicrobiomics.
Pharmaco- Subdisciplines
- Pharmacoeconomics: studies the economic aspects of medicine use on a large population basis.
- Pharmacogenetics: studies the influence of single pharmacogenes on drug responses.
- Pharmacogenomics: studies the influence of the whole genome on drug responses.
- Pharmacometabolomics: explores the effects of drugs on the body's production of metabolites.
- Pharmacomicrobiomics: explores the role of gut and other microbiomes on drug responses.
Naming Drugs
- Drug names can be bewildering, with no international body imposing uniform names.
- A given marketed drug can be known by three names: chemical, generic, and brand names.
The Fate of Pharmaceuticals in the GI-Tract
- Disintegration phase: tablets break down into granules and then smaller particles.
- Dissolution phase: drug dissolves in fluids of the gastrointestinal tract.
- Absorption phase: drug is absorbed into the systemic circulation.
- Four factors affect drug absorption: size, lipid solubility, ionisation, and functional groups.
Distribution and Membrane Drug Transporters
- Distribution occurs by passive diffusion and facilitated diffusion through cell membranes.
- Phospholipid bilayer and transporter proteins influence drug movement in and out of blood.
- Volume of distribution is the volume of body fluid into which the drug appears to be distributed.
Tissue Proteins and Partitioning into Fat
- Tissue proteins can be significant in skeletal muscle for some drugs.
- Obesity complicates drug disposition, with lipophilic drugs accumulating in fat.
Drug Metabolism (Biotransformation)
- Chemical alteration of drugs and foreign chemicals by drug-metabolising enzymes in the body.
- Metabolism generates multiple metabolites from a single parent drug.
- Metabolism usually decreases the half-life and biological activity of drugs.
General Features of Xenobiotic Metabolism
- Occurs mainly in the liver and gut wall.
- Cytochrome P450 (CYP) enzymes are the master catalysts of oxidative drug metabolism.
- Microsomes obtained from insect cells expressing human CYP genes are useful in in vitro predictions of drug metabolism.
Pharmacodynamics: Molecular Mechanisms of Drug Action
- Pharmacodynamics is the study of the effects of drugs on the function of living systems.
- It involves the interaction between a drug and components of the organism.
Drug Action
- Most drugs exert their effects by binding to protein targets such as receptors, ion channels, enzymes, and transporters.
- A drug must bind to a target to produce an effect.
Receptors
- Receptors are proteins that allow a chemical agent (drugs, hormones, neurotransmitters) to initiate a change in cell function.
- Receptors are the cell's 'sensing elements' and provide molecular communication between the chemical agent and the transduction process.
- Different cell types have different receptor profiles, which determines the hormones and neurotransmitters to which the cell responds.
Agonists and Antagonists
- Agonists mimic the actions of endogenous ligands and bind to the receptor to produce a response.
- Antagonists block the actions of endogenous ligands and bind to the receptor to prevent a response.
Ligand Selectivity
- Receptors show ligand selectivity, meaning each receptor type is activated by a small number of substances.
- Receptor activation requires a good 3-D "fit" between the agonist and receptor.
Selectivity of Drugs
- Useful drugs show selectivity, binding only to certain receptors to produce a specific response.
- Selectivity is reciprocal, meaning each drug only binds to certain receptors and each receptor recognises only certain drugs.
Limitations of Selectivity
- Selectivity is not absolute, as most drugs act on more than one receptor.
- Increasing the dose of a drug can activate other receptors, leading to adverse effects.
Drug-Induced Responses
- Drugs act by binding to specific drug targets, such as receptors, to produce a response.
- Agonist binding requires intermolecular forces between the agonist and receptor and is usually reversible.
- The strength of agonist binding is determined by the forward and backward rate constants.
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Description
Introduction to pharmacology, the branch of science that studies the effects of drugs on the human body, and pharmacognosy, the study of physical and biological properties of drugs from natural sources.