Pharmacokinetics and Pharmacodynamics

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Questions and Answers

Which of the following best describes pharmacokinetics?

  • The process by which the body absorbs, distributes, metabolizes, and excretes a drug. (correct)
  • The measurement of drug concentrations in the body over time.
  • The method of determining the most effective dosage regimen for a patient.
  • The study of how a drug affects the body's physiological functions.

What is the primary difference between pharmacokinetics and pharmacodynamics?

  • Pharmacokinetics involves the study of drug effects on the body, while pharmacodynamics involves the body's effect on drugs.
  • Pharmacokinetics describes how the body handles a drug, while pharmacodynamics describes how a drug affects the body. (correct)
  • Pharmacokinetics studies drug absorption, while pharmacodynamics studies drug metabolism.
  • Pharmacokinetics focuses on drug interactions, while pharmacodynamics focuses on drug toxicity.

Which factor primarily influences the distribution of a drug to different tissues in the body?

  • The patient's age and gender.
  • The drug's binding affinity to plasma proteins and tissue permeability. (correct)
  • The route of drug administration.
  • The rate of drug metabolism in the liver.

If a drug is said to have a narrow therapeutic index, what does this imply for a patient's treatment?

<p>The drug requires careful monitoring to avoid toxicity or ineffectiveness. (A)</p> Signup and view all the answers

How does renal dysfunction typically affect the pharmacokinetics of a drug primarily eliminated by the kidneys?

<p>It prolongs the drug's half-life and increases its plasma concentration. (C)</p> Signup and view all the answers

What is the most important consideration when individualizing drug treatment for a patient?

<p>The patient's specific clinical condition, concurrent medications, and potential drug interactions. (D)</p> Signup and view all the answers

Which of the following laboratory values is most important to monitor in a patient receiving a drug known to cause liver damage?

<p>Liver transaminases (AST, ALT). (A)</p> Signup and view all the answers

A patient with hypoalbuminemia is prescribed a highly protein-bound drug. How might this condition affect the drug's distribution and effect?

<p>It will increase the concentration of free drug in the plasma, potentially increasing its effect and risk of toxicity. (A)</p> Signup and view all the answers

What is the clinical significance of understanding a drug's half-life?

<p>It helps determine the time it takes for the drug concentration to reach steady state and how frequently the drug should be administered. (D)</p> Signup and view all the answers

Which of the following best explains the concept of 'first-pass metabolism'?

<p>The metabolism of a drug by the liver that occurs before it reaches systemic circulation following oral administration. (A)</p> Signup and view all the answers

A drug is known to induce CYP3A4 enzymes. What effect would this have on a second drug that is metabolized by CYP3A4?

<p>Decreased plasma concentration of the second drug, potentially reducing its therapeutic effect. (D)</p> Signup and view all the answers

Why is it important to consider a patient's genetic makeup (pharmacogenomics) when prescribing certain medications?

<p>To predict how a patient will respond to a drug based on their individual genetic variations. (C)</p> Signup and view all the answers

A patient is started on a medication that is a prodrug. What is a key consideration regarding the drug's action?

<p>The drug must be metabolized into an active form to have a therapeutic effect. (D)</p> Signup and view all the answers

Which of the following describes the concept of 'steady state' concentration in pharmacokinetics?

<p>The point at which the amount of drug absorbed equals the amount of drug eliminated over multiple dosing intervals. (C)</p> Signup and view all the answers

What is the primary rationale for using a loading dose of a drug?

<p>To rapidly achieve the desired therapeutic concentration. (A)</p> Signup and view all the answers

A drug that is a P-glycoprotein (P-gp) substrate is administered with a P-gp inhibitor. What is the expected outcome?

<p>Increased absorption and decreased elimination of the substrate drug. (A)</p> Signup and view all the answers

How does advanced age generally affect drug pharmacokinetics?

<p>Decreased renal clearance and decreased liver metabolism. (B)</p> Signup and view all the answers

If a drug has a high volume of distribution, what does this suggest about its distribution in the body?

<p>The drug is extensively distributed to tissues outside the bloodstream. (C)</p> Signup and view all the answers

What is the most important consideration when switching a patient from an intravenous (IV) formulation of a drug to an oral formulation?

<p>The oral bioavailability of the drug. (C)</p> Signup and view all the answers

A patient taking warfarin is started on a medication that inhibits CYP2C9. What is the most likely consequence?

<p>Increased risk of bleeding due to increased warfarin activity. (B)</p> Signup and view all the answers

How does understanding both pharmacokinetics and pharmacodynamics contribute to optimizing drug therapy?

<p>It allows for tailored dosing strategies based on how the body affects the drug and how the drug affects the body. (D)</p> Signup and view all the answers

What is the potential impact of genetic polymorphisms on drug metabolism and clinical outcomes?

<p>Genetic variations can alter enzyme activity, affecting drug metabolism and leading to either enhanced or diminished drug effects. (A)</p> Signup and view all the answers

What is the most important implication of a drug's high volume of distribution ($V_d$) for achieving therapeutic concentrations?

<p>The drug is likely to distribute extensively into tissues, potentially requiring a higher loading dose to achieve target plasma concentrations. (B)</p> Signup and view all the answers

In the context of drug interactions, what is the primary concern when a patient is taking an enzyme inducer along with another drug?

<p>The enzyme inducer will increase the metabolism of the other drug, potentially reducing its therapeutic effect. (A)</p> Signup and view all the answers

How does impaired liver function typically affect the pharmacokinetics of drugs that undergo extensive hepatic metabolism?

<p>It reduces drug metabolism, potentially leading to drug accumulation and increased risk of adverse effects. (C)</p> Signup and view all the answers

What is the key consideration when prescribing a drug with non-linear pharmacokinetics?

<p>Small changes in dose can lead to disproportionately large changes in plasma concentrations. (D)</p> Signup and view all the answers

Which of the following is the most important consideration when adjusting drug dosages for obese patients?

<p>Lipophilic drugs may have an increased volume of distribution, potentially requiring higher doses to achieve therapeutic concentrations. (C)</p> Signup and view all the answers

A patient is taking a drug that is a substrate of P-glycoprotein (P-gp). If a P-gp inducer is added to the patient's regimen, what is the likely effect on the substrate drug's plasma concentration?

<p>The plasma concentration of the substrate drug will decrease due to enhanced efflux. (D)</p> Signup and view all the answers

What is the anticipated effect on drug bioavailability when a drug is administered intravenously compared to orally?

<p>Intravenous administration typically results in 100% bioavailability, bypassing first-pass metabolism. (A)</p> Signup and view all the answers

Why is it crucial to consider a patient's renal function when prescribing drugs primarily eliminated by the kidneys?

<p>Renal impairment can lead to decreased drug clearance, potentially causing drug accumulation and toxicity. (D)</p> Signup and view all the answers

Which of the following best illustrates the concept of an inverse agonist?

<p>A drug that binds to a receptor and produces an effect opposite to that of an agonist. (B)</p> Signup and view all the answers

A patient experiences a severe anaphylactic reaction after receiving penicillin. Which type of adverse drug reaction does this represent?

<p>Type B reaction (Bizarre) (C)</p> Signup and view all the answers

Minoxidil, originally used to treat hypertension, was found to have a side effect of promoting hair growth. How is this classified?

<p>Beneficial side effect (B)</p> Signup and view all the answers

Which type of toxic effect is most likely to result from long-term exposure to low levels of a substance?

<p>Chronic toxicity (B)</p> Signup and view all the answers

Which of the following is a key characteristic of physical dependence?

<p>The development of tolerance, requiring more of the substance for the same effect (D)</p> Signup and view all the answers

Why is it important to distinguish between physical dependence and addiction when managing a patient's medication?

<p>Because physical dependence can occur with prescribed medications and may not involve compulsive drug-seeking behavior. (D)</p> Signup and view all the answers

What is the defining criterion for an allergic drug reaction?

<p>An immunological response to a medication that results in adverse effects (B)</p> Signup and view all the answers

A patient taking Drug A begins taking Drug B, which inhibits the CYP450 enzyme responsible for metabolizing Drug A. What is the most likely effect on Drug A's concentration in the body?

<p>The concentration of Drug A will increase. (B)</p> Signup and view all the answers

A patient is prescribed rifampicin, a CYP450 inducer. What effect will this have on a concurrently administered drug that is a CYP450 substrate?

<p>Reduced therapeutic effectiveness of the substrate drug. (C)</p> Signup and view all the answers

Which of the following mechanisms explains how food can increase the absorption of certain drugs?

<p>By delaying gastric emptying, which increases the time the drug stays in contact with the absorption surface (B)</p> Signup and view all the answers

Why might tetracycline absorption be reduced when taken with dairy products?

<p>Tetracycline forms insoluble complexes with calcium, reducing its absorption. (C)</p> Signup and view all the answers

How would you define a receptor in the context of pharmacodynamics?

<p>A protein that interacts with a physiological signal outside the cell and converts it into an effect inside the cells. (B)</p> Signup and view all the answers

Which of the following ligands is most likely to mimic the effect of an endogenous ligand when it binds to a receptor?

<p>Agonist (A)</p> Signup and view all the answers

If a drug is classified as a partial agonist, what is its characteristic effect on receptor activation?

<p>It binds and activates the receptor but produces a weaker response than a full agonist. (D)</p> Signup and view all the answers

Naloxone is an example of which type of ligand?

<p>Antagonist (B)</p> Signup and view all the answers

The observation that paracetamol overdoses are rising in Australia indicates a need to focus on which aspect of intervention?

<p>Educating the public on safe dosages and early intervention (A)</p> Signup and view all the answers

What is the crucial role of N-acetylcysteine (NAC) in paracetamol overdose management?

<p>To prevent the formation of the toxic metabolite of paracetamol (D)</p> Signup and view all the answers

If a patient presents to the emergency department after a paracetamol overdose, what is the most important initial action to take regarding liver function?

<p>Monitor liver function tests to assess the extent of liver damage. (C)</p> Signup and view all the answers

Which scenario best exemplifies a patient experiencing withdrawal symptoms due to physical dependence?

<p>A patient feeling anxious and irritable after abruptly stopping their antidepressant medication. (A)</p> Signup and view all the answers

What nursing intervention is most appropriate when a patient reports a rash and difficulty breathing after receiving a new medication?

<p>Immediately stop the medication, assess vital signs, and activate the emergency response system if needed. (D)</p> Signup and view all the answers

What is a key difference between pharmacodynamic and pharmacokinetic drug-drug interactions?

<p>Pharmacodynamic interactions involve alterations in drug action at target sites, while pharmacokinetic interactions affect drug concentrations. (A)</p> Signup and view all the answers

A patient is prescribed ketoconazole, an antifungal medication, along with another drug metabolized by CYP3A4. What is the primary concern regarding drug-drug interaction?

<p>Increased risk of side effects from the co-administered drug due to reduced metabolism (B)</p> Signup and view all the answers

How does increased blood flow to the gastrointestinal tract following a meal affect drug absorption?

<p>It increases drug absorption by promoting drug transport to absorption sites. (C)</p> Signup and view all the answers

What is the most likely outcome of combining a drug known to bind to dietary fiber with a high-fiber meal?

<p>Decreased drug absorption due to physical binding (C)</p> Signup and view all the answers

If a drug has a narrow therapeutic index, what specific monitoring and management strategies become essential to ensure patient safety?

<p>Frequent monitoring of drug plasma concentrations and patient response (B)</p> Signup and view all the answers

How does the presence of food, especially fat, enhance the absorption of highly lipophilic drugs such as griseofulvin?

<p>By stimulating bile secretion, which helps solubilize lipophilic drugs (B)</p> Signup and view all the answers

A patient is started on erythromycin while already taking a drug that is metabolized by CYP3A4. Which of the following is the most likely outcome of this drug interaction?

<p>Increased risk of toxicity from the CYP3A4 substrate due to reduced metabolism. (C)</p> Signup and view all the answers

A patient is diagnosed with chronic kidney disease. How might this condition alter the typical approach to drug dosing?

<p>Drug dosages may need to be decreased to prevent accumulation and toxicity. (C)</p> Signup and view all the answers

What specific patient education should a nurse provide regarding a medication known to have photosensitivity as a side effect?

<p>Use sunscreen and wear protective clothing when exposed to sunlight. (B)</p> Signup and view all the answers

Which of the following best describes the focus of pharmacodynamics?

<p>The study of the molecular, biochemical, and physiological effects of drugs on the body. (B)</p> Signup and view all the answers

What is the primary function of a receptor in the context of pharmacodynamics?

<p>To interact with a physiological signal and convert it into an intracellular effect. (A)</p> Signup and view all the answers

Which statement best characterizes the action of an agonist?

<p>It binds to a receptor and activates it, mimicking the effect of the endogenous ligand. (A)</p> Signup and view all the answers

How does a partial agonist differ from a full agonist in its mechanism of action?

<p>A partial agonist binds to and activates a receptor but produces a weaker response than a full agonist, even at full receptor occupancy. (D)</p> Signup and view all the answers

What is the primary mechanism by which an antagonist exerts its effect?

<p>By binding to a receptor and preventing other ligands from binding, thus blocking receptor activation. (C)</p> Signup and view all the answers

How does an inverse agonist differ from a typical antagonist?

<p>An inverse agonist produces an effect opposite to that of an agonist and reduces receptor activity below its baseline level. (B)</p> Signup and view all the answers

Which of the following best describes a Type A adverse drug reaction?

<p>Predictable, dose-dependent reactions related to the drug's pharmacological action. (D)</p> Signup and view all the answers

What is a key characteristic of Type B adverse drug reactions?

<p>They are rare, unpredictable, and often immune-mediated. (B)</p> Signup and view all the answers

How is a side effect best defined in the context of drug therapy?

<p>An unintended effect that occurs in addition to the primary intended outcome of a drug or treatment. (C)</p> Signup and view all the answers

Minoxidil's hair growth promotion is an example of what kind of drug effect?

<p>A beneficial side effect. (A)</p> Signup and view all the answers

What is a primary characteristic of toxic effects resulting from drug exposure?

<p>They cause damage at the cellular, tissue, or organ level. (D)</p> Signup and view all the answers

Chronic toxicity is best described as:

<p>Adverse effects resulting from long-term exposure to a substance. (D)</p> Signup and view all the answers

In the context of paracetamol overdose, what is the primary goal of early intervention?

<p>To prevent the formation of the toxic metabolite NAPQI. (D)</p> Signup and view all the answers

What is the primary role of N-acetylcysteine (NAC) in the treatment of paracetamol overdose?

<p>To enhance the detoxification of the toxic metabolite of paracetamol and prevent liver damage. (A)</p> Signup and view all the answers

What is a key characteristic that distinguishes physical dependence from addiction?

<p>Physical dependence is a physiological adaptation to a substance resulting in withdrawal symptoms, while addiction involves compulsive drug-seeking behavior despite harm. (B)</p> Signup and view all the answers

What is the primary criterion that defines an allergic drug reaction?

<p>An immunological response to a medication resulting in adverse effects. (D)</p> Signup and view all the answers

Which of the following is a typical clinical manifestation of an allergic drug reaction?

<p>Sudden decrease in blood pressure and difficulty breathing. (C)</p> Signup and view all the answers

What is the priority nursing intervention when managing a patient experiencing a serious allergic drug reaction?

<p>Stopping medication administration immediately and assessing airway, breathing, and circulation. (D)</p> Signup and view all the answers

What is the fundamental difference between pharmacokinetic and pharmacodynamic drug-drug interactions?

<p>Pharmacokinetic interactions affect drug absorption, distribution, metabolism, or excretion, while pharmacodynamic interactions affect drug action at target sites. (C)</p> Signup and view all the answers

If a drug inhibits CYP450 enzymes, what effect does this have on the concentration of other drugs metabolized by these enzymes?

<p>It increases the concentration of the other drugs. (D)</p> Signup and view all the answers

How does CYP450 induction affect the metabolism of other drugs?

<p>It speeds up the metabolism of other drugs. (C)</p> Signup and view all the answers

What is the most likely clinical implication of CYP450 induction on a drug regimen?

<p>Reduced therapeutic effectiveness of affected drugs. (D)</p> Signup and view all the answers

How does increased blood flow to the gastrointestinal tract typically affect drug absorption?

<p>It increases drug absorption by delivering more drug to the absorption sites. (B)</p> Signup and view all the answers

Which of the following is most likely to decrease drug absorption?

<p>Chemical binding of the drug to food components. (B)</p> Signup and view all the answers

Why might the absorption of tetracycline be reduced when taken with dairy products?

<p>Tetracycline forms insoluble complexes with calcium in dairy products. (A)</p> Signup and view all the answers

How does the consumption of food, particularly fats, enhance the absorption of highly lipophilic drugs?

<p>By increasing the drug's solubility and lymphatic absorption. (C)</p> Signup and view all the answers

A patient is prescribed a drug known to bind to dietary fiber. What is the most likely effect of taking this medication with a high-fiber meal?

<p>Decreased drug absorption due to binding of the drug to the fiber. (D)</p> Signup and view all the answers

If a patient is taking a drug that is a CYP3A4 substrate and begins taking erythromycin, what is the most likely outcome of this drug interaction?

<p>Increased plasma concentration of the CYP3A4 substrate. (B)</p> Signup and view all the answers

A patient is diagnosed with chronic kidney disease. How might this condition influence drug dosing?

<p>It usually requires lower drug doses or less frequent administration to avoid drug accumulation. (D)</p> Signup and view all the answers

What specific patient education should a nurse provide regarding a medication known to cause photosensitivity?

<p>Apply sunscreen and wear protective clothing when exposed to sunlight. (B)</p> Signup and view all the answers

Flashcards

Pharmacokinetics

The study of what the body does to a drug, involving absorption, distribution, metabolism, and excretion (ADME).

Pharmacodynamics

The study of what a drug does to the body, involving the drug's mechanism of action and its effects.

Factors impacting treatment

Factors such as age, genetics, disease state, and other medications that can alter drug response.

Individualising Treatment

Adjusting a medication regimen to achieve optimal therapeutic outcomes based on individual patient characteristics.

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Monitoring Treatment

The process of regularly assessing drug concentrations or effects to ensure safety and efficacy.

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Clinical Reasoning Skills

The use of logical and analytical processes to evaluate patient information and make informed decisions about treatment.

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Pharmacokinetics principle

The study of how drugs are processed in the body, impacting selection and individualization of treatment.

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Pharmacodynamics principle

The study of how drugs affect the body, influencing the choice and monitoring of treatments.

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Clinical reasoning

The thinking process doctors use to evaluate info and make treatment decisions.

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Patient factors

Characteristics such as age, weight, kidney function, and liver function that influence drug response.

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Selecting Treatment

The process of choosing the right medication based on understanding how the body handles drugs and how drugs affect the body.

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Treatment Monitoring

Regularly checking a patient's condition and drug levels to ensure the treatment is safe and effective.

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Receptor

A protein that interacts with a physiological signal outside the cell and converts it into an effect inside the cells.

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Ligand

A molecule that binds to a protein/receptor to trigger a biological response.

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Agonist

Ligand that binds to a receptor and activates it to produce a biological response, mimicking the natural ligand.

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Partial Agonist

Binds to and activates a receptor, producing a weaker response than a full agonist.

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Antagonist

Binds to a receptor but does not activate it, blocking the receptor's response.

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Inverse Agonist

Binds to a receptor and produces the opposite effect of an agonist.

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Type A Reactions

Predictable, dose-dependent adverse effects related to the drug's pharmacological action.

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Type B Reactions

Unpredictable, dose-independent adverse effects not related to the drug's known actions.

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Side Effect

Unintended effect that occurs in addition to the primary intended outcome of a drug.

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Toxic Effects

Adverse reactions or harmful consequences causing damage at the cellular, tissue, or organ level.

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Acute Toxicity

Immediate effects from short-term exposure to a toxic substance.

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Chronic Toxicity

Effects from long-term exposure to a toxic substance.

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Organ-Specific Toxicity

Damage to particular organs from exposure to a toxic substance.

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Genotoxicity

Damage to genetic material from exposure to a toxic substance.

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Carcinogenicity

Cancer-causing effects from exposure to a toxic substance.

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Physical Dependence

Physiological state where the body adapts to regular drug use, requiring continued use to avoid withdrawal.

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Tolerance

The need for more of a substance to achieve the same effect.

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Withdrawal Symptoms

Symptoms that occur when stopping the use of a substance the body is dependent on.

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Physical Dependence Character

Biological adaptation to a substance, resulting in predictable withdrawal symptoms.

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Allergic Drug Reaction

Immunological response to a medication resulting in adverse effects.

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Anaphylaxis

A severe, life-threatening allergic reaction.

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Drug-Drug Interactions

Occur when two or more drugs interact, altering the effectiveness or side effects of one or both.

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Pharmacokinetic Interactions

Affect drug absorption, distribution, metabolism, or excretion.

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Drug-Drug Interactions Metabolic Changes

Involving the cytochrome P450 (CYP450) enzyme system in the liver.

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CYP450 Inhibition

Prevents the metabolism of other drugs that are substrates of these enzymes.

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CYP450 Induction

Increases the metabolism rate of other drugs that are substrates of these enzymes.

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Drug-Food Interactions

Occur when food affects drug absorption, either increasing or decreasing it.

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Food Increases Drug Absorption

Increased blood flow to the gastrointestinal tract, delayed gastric emptying, stimulation of bile secretion.

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Food Decreases Drug Absorption

Physical or chemical binding of the drug to food components.

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Pharmacodynamics Defined

The study of the molecular, biochemical, and physiologic effects of drugs on the body.

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Study Notes

Pharmacodynamics Core Concepts

  • Pharmacodynamics is the study of the molecular, biochemical, and physiological effects of drugs on the human body.
  • A receptor is a protein that interacts with a physiological signal outside the cell and converts it into an effect inside the cells.

Drug-receptor interactions:

  • A ligand is a molecule that binds to a specific site on a protein or receptor to trigger a biological response.
  • An agonist is a ligand that binds to a receptor and activates it to produce a biological response, mimicking the effect of the endogenous ligand, such as adrenaline (epinephrine) for beta-adrenergic receptors.
  • A partial agonist binds to and activates a receptor, but produces a weaker response than a full agonist, even at maximum receptor occupancy; buprenorphine is a partial agonist at the mu-opioid receptor.
  • An antagonist binds to a receptor but does not activate it, blocking or dampening the receptor's response by preventing other ligands from binding; naloxone is an antagonist at opioid receptors.
  • An inverse agonist binds to a receptor and produces an effect opposite to that of an agonist, reducing the receptor's baseline activity below its normal level; beta-carbolines act as inverse agonists at GABA receptors.

Factors Impacting Treatment Selection

  • Applying clinical reasoning skills impacts treatment selection

Monitoring Treatment

  • Applying clinical reasoning skills impacts monitoring treatment

Individualizing Treatment

  • Applying clinical reasoning skills impacts individualising treatment

Adverse drug effects :

  • Type A reactions (augmented) are predictable, dose-dependent adverse effects related to the pharmacological action of the drug, accounting for approximately 80% of adverse drug reactions (e.g., bleeding with high doses of anticoagulants like warfarin).
  • Type B reactions (bizarre) are unpredictable, dose-independent adverse effects not related to the drug's known pharmacological actions, typically rare but can be severe and often immune-mediated (e.g., anaphylactic reactions to penicillin).
  • A side effect is an unintended effect that occurs in addition to the primary intended outcome of a drug or treatment; some can be beneficial (e.g., minoxidil promoting hair growth).
  • Toxic effects are adverse reactions or harmful consequences that occur when a substance interacts with living organisms, causing damage at the cellular, tissue, or organ level (e.g., mercury poisoning leading to neurological damage).
  • Acute toxicity refers to immediate effects from short-term exposure.
  • Chronic toxicity refers to effects from long-term exposure.
  • Organ-specific toxicity involves damage to particular organs.
  • Genotoxicity is damage to genetic material.
  • Carcinogenicity refers to cancer-causing effects.
  • The severity of toxic effects depends on factors including dose, exposure route and duration, and individual susceptibility.

Physical dependence vs Addiction

  • Key characteristics of physical dependence include development of tolerance and presence of withdrawal symptoms when stopping use.
  • Physical dependence is a biological adaptation to a substance, leading to predictable withdrawal symptoms, and can occur with prescribed medications, generally resolving with supervised discontinuation.
  • Addiction is a complex behavioral disorder characterized by compulsive drug-seeking behavior and loss of control over use, continuing despite negative consequences, and significantly impacting daily functioning.

Allergic reactions

  • An allergic drug reaction is defined by an immunological response to a medication that results in adverse effects.
  • It must involve the immune system's response, typically involving IgE antibodies, rather than just being an unwanted side effect.
  • Clinical manifestations of allergic drug reactions:
    • Skin reactions (hives, rash, itching)
    • Respiratory symptoms (wheezing, difficulty breathing)
    • Cardiovascular symptoms (hypotension, tachycardia)
    • Gastrointestinal symptoms (nausea, vomiting)
    • Anaphylaxis (severe, life-threatening reaction)
  • Nursing considerations for managing serious allergic drug reactions include immediate assessment and recognition, emergency interventions, and documentation and follow-up.
    • Monitor vital signs
    • Assess airway, breathing, circulation
    • Recognize early signs of anaphylaxis
    • Stop medication administration immediately
    • Activate emergency response system if needed
    • Administer prescribed emergency medications (e.g., epinephrine)
    • Maintain IV access
    • Record all observations and interventions
    • Update allergy documentation
    • Provide patient education
    • Ensure proper reporting of adverse drug reaction

Drug-Drug Interactions

  • Drug-drug interactions occur when two or more drugs interact with each other, altering the effectiveness or side effects of one or both medications, and can be pharmacokinetic or pharmacodynamic.
  • Many drug interactions occur through changes in drug metabolism, particularly involving the cytochrome P450 (CYP450) enzyme system.
  • CYP450 Inhibition:
    • A drug inhibits CYP450 enzymes, preventing the metabolism of other drugs that are substrates of these enzymes.
    • Examples: ketoconazole and erythromycin
    • Inhibition leads to increased concentrations of affected drugs, potentially causing increased side effects, toxicity, and requiring dose adjustments.
  • CYP450 Induction:
  • A drug induces CYP450 enzymes, increasing the metabolism rate of other drugs that are substrates of these enzymes.
  • Examples: rifampicin and carbamazepine
  • Induction leads to decreased concentrations of affected drugs, potentially causing reduced therapeutic effectiveness, treatment failure, and requiring dose adjustments.

Drug-food interactions

  • Food can increase drug absorption through:
    • Increased blood flow to the gastrointestinal tract
    • Delayed gastric emptying
    • Stimulation of bile secretion
    • Enhanced solubility of lipophilic drugs by food components (especially fats)
    • Food-induced increase in gastric pH
    • Examples: griseofulvin, albendazole, and atovaquone
  • Food can decrease drug absorption through:
    • Physical or chemical binding of the drug to food components
    • Competition for absorption mechanisms
    • Formation of non-absorbable complexes
    • Increased viscosity of gastrointestinal contents
    • pH changes that may reduce ionization of weak bases
    • Examples: tetracycline antibiotics, levothyroxine, and certain fluoroquinolones like ciprofloxacin

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