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Questions and Answers
Which of the following mechanisms describe how drugs produce effects in the body?
Which of the following mechanisms describe how drugs produce effects in the body?
Non-steroidal anti-inflammatory agents like Ibuprofen affect enzyme activity.
Non-steroidal anti-inflammatory agents like Ibuprofen affect enzyme activity.
True
What type of molecules do drugs mostly bind to in order to exert their effects?
What type of molecules do drugs mostly bind to in order to exert their effects?
Proteins
Mannitol causes __________ diuresis by changing osmotic balance across membranes.
Mannitol causes __________ diuresis by changing osmotic balance across membranes.
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Match each drug action to its example:
Match each drug action to its example:
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Which of the following is an example of an anti-metabolite?
Which of the following is an example of an anti-metabolite?
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What is the primary focus of pharmacodynamics?
What is the primary focus of pharmacodynamics?
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Receptors are found only on the surface of cells.
Receptors are found only on the surface of cells.
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What is the role of enzymes in pharmacology?
What is the role of enzymes in pharmacology?
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Pharmacokinetics focuses on the effects of drugs on the body.
Pharmacokinetics focuses on the effects of drugs on the body.
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Define pharmacology.
Define pharmacology.
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_______ refers to the movement of the drug in and alteration of the drug by the body.
_______ refers to the movement of the drug in and alteration of the drug by the body.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Which of the following does not fall under the definition of a drug?
Which of the following does not fall under the definition of a drug?
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Drug-receptor interactions only occur at the molecular level.
Drug-receptor interactions only occur at the molecular level.
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List the two main divisions of pharmacology.
List the two main divisions of pharmacology.
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What does adenylyl cyclase convert ATP into?
What does adenylyl cyclase convert ATP into?
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CAMP is considered a second messenger in cellular signaling pathways.
CAMP is considered a second messenger in cellular signaling pathways.
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What process leads to the addition of phosphate groups to other proteins inside the cytoplasm?
What process leads to the addition of phosphate groups to other proteins inside the cytoplasm?
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Ligands that bind to intracellular receptors include __________ hormones.
Ligands that bind to intracellular receptors include __________ hormones.
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Match the following second messengers with their correct functions:
Match the following second messengers with their correct functions:
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Which type of receptors are usually linked to inactivated enzymes and primarily protein kinases?
Which type of receptors are usually linked to inactivated enzymes and primarily protein kinases?
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Drugs acting on intracellular receptors produce immediate effects because they affect gene transcription directly.
Drugs acting on intracellular receptors produce immediate effects because they affect gene transcription directly.
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According to A.J. Clark, what is the relationship between drug response and receptor occupation?
According to A.J. Clark, what is the relationship between drug response and receptor occupation?
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What is the therapeutic index (TI) of digitalis?
What is the therapeutic index (TI) of digitalis?
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A drug with a TI of less than 1 is considered usable.
A drug with a TI of less than 1 is considered usable.
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What formula is used to calculate the therapeutic index (TI)?
What formula is used to calculate the therapeutic index (TI)?
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Penicillin has a therapeutic index of _____.
Penicillin has a therapeutic index of _____.
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Match the following drug characteristics with their descriptions:
Match the following drug characteristics with their descriptions:
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What occurs in reversible antagonist-receptor interaction?
What occurs in reversible antagonist-receptor interaction?
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An irreversible competitive antagonist can be displaced by increasing doses of an agonist.
An irreversible competitive antagonist can be displaced by increasing doses of an agonist.
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What is a characteristic of non-competitive antagonists?
What is a characteristic of non-competitive antagonists?
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In irreversible competition, the antagonist dissociates __________ from the receptor.
In irreversible competition, the antagonist dissociates __________ from the receptor.
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Which of the following best describes the action of an antagonist?
Which of the following best describes the action of an antagonist?
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Match the types of antagonism with their descriptions:
Match the types of antagonism with their descriptions:
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The binding of an antagonist can induce a __________ change in the receptor.
The binding of an antagonist can induce a __________ change in the receptor.
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Which drug has the greater maximum therapeutic effect if drug A shows more potency than drug B?
Which drug has the greater maximum therapeutic effect if drug A shows more potency than drug B?
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What does a full agonist exhibit in comparison to a partial agonist?
What does a full agonist exhibit in comparison to a partial agonist?
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Efficacy measures the amount of a drug needed to produce a specific response.
Efficacy measures the amount of a drug needed to produce a specific response.
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What is the term for the tendency of a drug to bind to a receptor?
What is the term for the tendency of a drug to bind to a receptor?
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The ultimate achievable response of a drug is referred to as Emax and the index of potency is known as _____?
The ultimate achievable response of a drug is referred to as Emax and the index of potency is known as _____?
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Which factor characterizes a drug's intrinsic activity?
Which factor characterizes a drug's intrinsic activity?
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Spare receptors refer to a situation where full agonists occupy all available receptors leaving none for endogenous substances.
Spare receptors refer to a situation where full agonists occupy all available receptors leaving none for endogenous substances.
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What is the mechanism by which agonists interact with receptors?
What is the mechanism by which agonists interact with receptors?
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Study Notes
Introduction to Pharmacology & Pharmacodynamics
- Pharmacology is the study of the effects of drugs on physiological and pathophysiological processes.
- It is a branch of medical science that deals with the properties and characteristics of chemical agents (drugs) used for medicinal or other purposes.
- It is derived from Greek: Pharmacon (drug): logos (study or discourse).
- Pharmacology is divided into two main branches: pharmacodynamics and pharmacokinetics.
Aim/Objectives
- Define pharmacology
- Distinguish between pharmacodynamics and pharmacokinetics
- Describe drug actions at molecular, cellular, and organ levels
- Describe different types of drug-receptor interactions
- Describe drug effects over time
- Describe drug safety indices and how they are measured
Outcomes/Expectations
- Students will know the definition of pharmacology as a medical science.
- Students will know the different types of pharmacological studies.
- Students will be able to briefly describe basic drug actions at molecular and cellular levels.
- Students will be able to describe different types of drug-receptor interactions.
- Students will understand and be able to interpret dose-response relations under different conditions.
- Students will know drug effects or actions over time.
- Students will be familiar with drug safety indices and how they are measured.
Pharmacology
- A drug is an active chemical entity present in a medical product used for diagnosis, prevention, or treatment/cure of a disease.
- This definition does not include contraceptives or drugs used to improve health.
- A drug can be a pharmacodynamic agent (designed for pharmacodynamic effects) or a chemotherapeutic agent (designed to inhibit/kill invading parasites/malignant cells).
- Drugs are also used to refer to the use of illicit or inappropriate use of licit drugs merely for physical or mental gratification; potential for dependence/addiction/abuse.
Pharmacological Studies
- Includes molecular studies from chemical molecules up to genes (in vitro); signal transduction cascades; gene cloning; expression
- Includes cellular studies using cells and reduced tissue (in vitro, ex vivo); cancer cell lines; dissociated neurons/myocytes; slices
- Includes organ studies (ex vivo) using isolate heart/intestines/muscles/lungs
- Includes whole animal studies (in vivo); disease models; genetic knock-in, knock-out; chemical lesioning
Techniques
- Biochemistry
- Biophysics
- Radiochemistry
- Microscopy
Other Aspects of Pharmacology
- Toxicology: study of unwanted or poisonous & adverse effects of drugs and chemicals (household, environmental, industrial, agricultural, homicidal); detection, prevention, and treatment of poisonings
- Pharmacotherapeutics: application of pharmacological information together with knowledge of the disease to prevent, mitigate, or cure. Involves selection of an appropriate drug, dosage and duration considering patient specifics.
Aspects of Pharmacology: Clinical Pharmacology
- Scientific study of drugs (both old and new) in humans, including pharmacodynamic and pharmacokinetic investigation in healthy volunteers and patients (Clinical Trials).
- Evaluation of drug efficacy and safety; comparative trials with other treatments; surveillance of drug use patterns; adverse effects.
- Aims to generate data for optimum use of drugs and practice of evidence-based medicine.
- Subspecialties: Systems/Disease based e.g. Neuropharmacology, Respiratory Pharmacology, GI Pharmacology, Molecular Pharmacology, Cellular Pharmacology, Cardiovascular Pharmacology, Immunopharmacology, Cancer Pharmacology, Pharmacogenetics/genomics etc
Introduction to Pharmacodynamics
- The study of the effects of a drug on the living system (i.e what the drug does when it gets there).
- Effects are produced by non-receptor mechanisms and receptor interactions.
- Drugs mostly act by binding to protein targets such as enzymes, carrier molecules, ion channels, and receptors.
Non-receptor Mechanisms
- Actions on enzymes: Enzymes are biological catalysts that speed chemical reactions. Drugs that alter enzyme activity alter processes catalyzed by the enzyme.
- Examples include nonsteroidal anti-inflammatory agents and monoamine oxidase inhibitors.
- Changing physical properties: Examples include mannitol, which alters osmotic balance.
- Changing cell membrane permeability to ions: Examples include lidocaine (blocks sodium channels) and verapamil (blocks calcium channels).
- Combining with other chemicals: Drugs such as antacids combine with other chemicals.
Receptor Concept
- Receptors are macromolecular components of a cell (on the surface or inside the cytoplasm) with which a drug interacts to produce a response or effect.
- Usually there is a conformational change.
- Binding site specificity and drug usefulness. No complete/absolute specificity, (selectivity, side-effects)
- Affinity- the tendency of a drug to bind to a receptor.
- Intrinsic activity (a): ability of a drug to induce/cause a response after binding to a receptor (a = +1 to -1).
- Efficacy: ability of a drug to produce (the maximum possible) physiological response(a = +1 =full agonist).
Occupancy theory of drug receptors
- A.J. Clark's theory (1926 & 1937): Pharmacological response depends on the proportion of receptors occupied.
- The maximum response occurs when all receptors are occupied.
- Relationship between receptor occupancy and response is usually linear.
Types of Receptors
- Channel-linked receptors: Ligand binds to receptor, causing opening or closing of ion channel pores (e.g., calcium channel blockers, local anesthetics).
- G-protein-coupled receptors (GPCRs): 7-transmembrane receptors, have an intermediate binding protein (G-protein) with alpha, beta and gamma subunits; activated G-protein alters effector proteins like adenylyl cyclase; generates second messengers like cAMP.
- Enzyme-linked receptors: transmembrane receptors with intracellular enzyme domains; ligand binding activates enzymes; leads to phosphorylation (e.g. tyrosine kinase receptors for growth factors, insulin).
Second Messengers
- Derivatives of phosphatidylinositol bisphosphates (PIP2): inositol triphosphate (IP3), diacylglycerol (DAG), calcium ions
- cAMP, cGMP
Intracellular/Nuclear receptors
- Receptors located inside the cell, not on the cell membrane.
- Ligands are usually lipophilic hormones. (steroidal hormones, vitamin D, thyroid hormone).
- Ligands bind, receptors are activated, moving into the nucleus, interacting with nuclear DNA to affect gene expression, protein synthesis in the target cell.
- Drugs acting on these receptors are generally slow-acting, because gene transcription needs time.
Summary Receptor types
- Agonist, Binding, Activation of conductance, G-Protein Activation, Generation of receptor messenger, Phosphorylation, Transporr to nucleus, activation of transcription and translation.
Dose-response curves: Potency and Efficacy
- EC50 (half maximal effective concentration) index of potency (amount of drug to produce a response).
- Emax (maximum effective response) measure of efficacy (ability of a drug to cause a physiological response).
- A full agonist has greater efficacy than a partial agonist.
- Potency and efficacy are related to but different measures.
Receptor Interactions
- Binding-site specificity, selectivity, side effects.
- Affinity (tendency of drug to bind receptor).
- Intrinsic activity (ability of a drug to induce a response after binding).
- Efficacy (ability to produce maximum physiological response).
Therapeutic Index
- Ratio of the lethal dose (LD50) to the effective dose (ED50).
- A safe drug has a TI > 1.
- Used in the context of adverse drug reactions.
Time Response Relationships
- Time course of effect; Latency (time to first observe effect); Duration of Response (time from start of effect to end); maximal/peak effect.
- Route of administration effects time to onset and duration ie IV versus IM versus SC.
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Description
This quiz explores the fundamental concepts of pharmacology and pharmacodynamics. It covers drug interactions, safety indices, and the physiological effects of drugs. Students will gain an understanding of essential pharmacological principles and terminology.
