Video Library
Please set your exam date
Pharmacokinetics and pharmacodynamics
Study Questions
Pharmacokinetics
A nurse is preparing to administer a medication that has a narrow therapeutic index. What action should the nurse take?
Explanation
A medication with a narrow therapeutic index has a small margin of safety between its therapeutic and toxic doses. The nurse should hold the medication and notify the provider to ensure that the client’s drug levels are within the therapeutic range and to avoid potential toxicity.
a. Administering the medication as prescribed could result in toxicity if the client’s drug levels are not within the therapeutic range.
c. Administering half the dose of the medication is not appropriate without consulting the provider and monitoring the client’s drug levels.
d. Administering the medication with food or milk may affect its absorption but does not prevent potential toxicity.
A nurse is preparing to administer a medication that undergoes extensive first-pass metabolism. What route of administration should be used?
Explanation
First-pass metabolism refers to the metabolism of a drug by the liver before it reaches systemic circulation. Drugs that undergo extensive first-pass metabolism have a lower bioavailability when administered orally because a significant portion of the drug is metabolized before it reaches systemic circulation. Intravenous administration bypasses first-pass metabolism and delivers the drug directly into systemic circulation.
a. Oral administration would result in lower bioavailability due to first-pass metabolism.
c. Subcutaneous administration may also be subject to first-pass metabolism.
d. Intramuscular administration may also be subject to first-pass metabolism.
A nurse is preparing to administer a lipophilic medication to a client with a high body fat percentage. What should the nurse consider?
Explanation
Lipophilic medications are soluble in fat and can accumulate in adipose tissue, reducing their concentration in plasma and potentially reducing their therapeutic effect. A client with a high body fat percentage may require a higher dose of a lipophilic medication to achieve therapeutic levels.
b. The client may require a higher, not lower, dose of the medication due to accumulation in adipose tissue.
c. More frequent dosing may not be necessary if an appropriate dose is administered.
d. The client’s body fat percentage can affect pharmacokinetics by altering distribution of lipophilic medications.
A nurse is preparing to administer a weakly acidic medication to a client with an elevated gastric pH due to antacid use. What should the nurse consider?
Explanation
Weakly acidic medications are more readily absorbed in an acidic environment because they are more likely to be in their non-ionized, lipid-soluble form which can easily cross cell membranes and enter systemic circulation. An elevated gastric pH due to antacid use can reduce absorption of weakly acidic medications by increasing ionization and reducing lipid solubility.
a. The medication will have decreased, not increased, absorption in an alkaline environment due to increased ionization.
c. The antacid can affect absorption by altering gastric pH and increasing ionization of weakly acidic medications.
d. The antacid can affect absorption but does not directly affect excretion of weakly acidic medications.
A nurse is preparing to administer a prodrug that requires activation by hepatic enzymes.What should be considered when administering this drug?
Explanation
A prodrug is an inactive compound that requires conversion into its active form by metabolic processes such as hepatic enzyme activation.Giving a prodrug with an enzyme inducer can increase the activity of the hepatic enzymes responsible for converting the prodrug into its active form, potentially increasing its efficacy.
a.Giving the drug with food may affect its absorption but does not directly affect its activation by hepatic enzymes.
b.Giving the drug with food may affect its absorption but does not directly affect its activation by hepatic enzymes.
c.Giving the drug with an enzyme inducer, not an enzyme inhibitor, can increase its efficacy by increasing hepatic enzyme activity.
A nurse is preparing to administer a medication that is primarily excreted by the kidneys.What should be considered when administering this drug to a client with renal impairment?
Explanation
Medications that are primarily excreted by the kidneys can accumulate in clients with renal impairment, potentially leading to toxicity.A client with renal impairment may require a lower dose of a medication that is primarily excreted by the kidneys to avoid accumulation and toxicity.
a.The client may require a lower, not higher, dose of the medication due to reduced renal excretion.
c.More frequent dosing may not be necessary if an appropriate dose is administered.
d.The client’s renal function can affect pharmacokinetics by altering excretion of medications that are primarily eliminated by the kidneys.
A nurse is preparing to administer a medication that is highly protein bound.What should be considered when administering this drug to a client with hypoalbuminemia?
Explanation
Medications that are highly protein bound bind to plasma proteins such as albumin, reducing their free fraction and potentially reducing their therapeutic effect.A client with hypoalbuminemia may have an increased free fraction of a highly protein-bound medication due to reduced protein binding, potentially increasing its therapeutic effect.
b.The client may have an increased, not decreased, free fraction of the drug due to reduced protein binding.
c.An increased volume of distribution may occur if protein binding is reduced, but this is not directly related to hypoalbuminemia.
d.The client’s albumin levels can affect pharmacokinetics by altering protein binding of highly protein-bound medications.
A nurse is preparing to administer a medication that undergoes enterohepatic recirculation.What should be considered when administering this drug?
Explanation
Enterohepatic recirculation refers to the process by which a drug or its metabolites are excreted into bile, reabsorbed from the intestines, and returned to the liver.Medications that undergo enterohepatic recirculation can have a longer half-life due to repeated reabsorption and recirculation.
a.The drug will have a longer, not shorter, half-life due to repeated reabsorption and recirculation.
c.Enterohepatic recirculation can affect half-life but does not directly affect bioavailability.
d.Enterohepatic recirculation can affect half-life but does not directly affect bioavailability.
A nurse is preparing to administer a medication that induces CYP450 enzymes.What should be considered when administering this drug with other medications?
Explanation
CYP450 enzymes are responsible for metabolizing many medications.Induction of CYP450 enzymes can increase their activity and accelerate metabolism of other medications that are substrates for these enzymes, potentially reducing their therapeutic effect and increasing the risk of drug interactions.
b.There is an increased, not decreased, risk of drug interactions due to accelerated metabolism of other medications.
c.There is an increased risk of drug interactions due to accelerated metabolism of other medications.
d.CYP450 induction can affect pharmacokinetics by altering metabolism of other medications that are substrates for these enzymes.
A nurse is preparing to administer a medication that inhibits P-glycoprotein.What should be considered when administering this drug with other medications?
Explanation
P-glycoprotein is a membrane protein that pumps certain drugs out of cells and can affect their absorption, distribution, and elimination. Inhibition of P-glycoprotein can increase the concentration of other medications that are substrates for this protein, potentially increasing their therapeutic effect and the risk of drug interactions.
b. There is an increased, not decreased, risk of drug interactions due to increased concentration of other medications that are substrates for P-glycoprotein.
c. There is an increased risk of drug interactions due to increased concentration of other medications that are substrates for P-glycoprotein.
d. P-glycoprotein inhibition can affect pharmacokinetics by altering absorption, distribution, and elimination of other medications that are substrates for this protein.
Pharmacodynamics
A nurse is preparing to administer a medication that acts as an agonist at a specific receptor. What effect will this medication have?
Explanation
An agonist is a medication that binds to a specific receptor and activates it, increasing its activity. A medication that acts as an agonist at a specific receptor will increase the activity of that receptor.
b. An agonist increases, not decreases, the activity of the receptor it binds to.
c. An agonist has an effect on the activity of the receptor it binds to by increasing its activity.
d. An agonist activates, not blocks, the activity of the receptor it binds to.
A nurse is preparing to administer a medication that acts as an antagonist at a specific receptor. What effect will this medication have?
Explanation
An antagonist is a medication that binds to a specific receptor and blocks its activation, preventing other medications or endogenous ligands from activating it. A medication that acts as an antagonist at a specific receptor will block the activity of that receptor.
a. An antagonist blocks, not increases, the activity of the receptor it binds to.
b. An antagonist does not directly decrease the activity of the receptor it binds to but prevents its activation by other medications or endogenous ligands.
c. An antagonist has an effect on the activity of the receptor it binds to by blocking its activation.
A nurse is preparing to administer a medication that has a high affinity for its target receptor. What does this mean?
Explanation
Affinity refers to the strength of binding between a medication and its target receptor. A medication with a high affinity for its target receptor will bind strongly to that receptor.
b. A medication with a high affinity for its target receptor will bind strongly, not weakly, to that receptor.
c. Affinity refers to binding strength and does not directly determine efficacy, which refers to the ability of a medication to produce a therapeutic effect once bound to its target receptor.
d. Affinity refers to binding strength and does not directly determine efficacy, which refers to the ability of a medication to produce a therapeutic effect once bound to its target receptor.
A nurse is preparing to administer a medication that has high intrinsic efficacy.What does this mean?
Explanation
Intrinsic efficacy refers to how well a drug activates receptors once bound.A drug with high intrinsic efficacy produces maximal response when bound and can activate receptors fully.
b.A drug with high intrinsic efficacy produces maximal response when bound and can activate receptors fully
c.A drug with high intrinsic efficacy produces maximal response when bound and can activate receptors fully
d.Intrinsic efficacy affects pharmacodynamics by determining how well a drug activates receptors once bound
A nurse is preparing to administer two medications with additive effects.What should be considered when administering these drugs?
Explanation
Additive effects occur when two drugs produce similar effects and their combined effect is equal to sum of their individual effects.When administering two drugs with additive effects,the nurse should consider their combined effect and adjust dosing accordingly.
a.Additive effects occur when two drugs produce similar effects and their combined effect is equal to sum of their individual effects
b.Additive effects occur when two drugs produce similar effects and their combined effect is equal to sum of their individual effects
d.Additive effects affect pharmacodynamics by determining how two drugs interact when given together
A nurse is preparing to administer two medications with synergistic effects.What should be considered when administering these drugs?
Explanation
Synergistic effects occur when two drugs produce similar or complementary effects and their combined effect is greater than the sum of their individual effects.When administering two drugs with synergistic effects,the nurse should consider their combined effect and adjust dosing accordingly.
b.Synergistic effects occur when two drugs produce similar or complementary effects and their combined effect is greater than the sum of their individual effects
c.Synergistic effects occur when two drugs produce similar or complementary effects and their combined effect is greater than the sum of their individual effects
d.Synergistic effects affect pharmacodynamics by determining how two drugs interact when given together
A nurse is preparing to administer a medication that has a low therapeutic index.What should be considered when administering this drug?
Explanation
Therapeutic index refers to the ratio between the toxic dose and the therapeutic dose of a drug.A drug with a low therapeutic index has a narrow margin of safety,meaning that the difference between its toxic and therapeutic doses is small.When administering a drug with a low therapeutic index,the nurse should carefully monitor the client for signs of toxicity.
a.A drug with a low therapeutic index has a narrow margin of safety,meaning that the difference between its toxic and therapeutic doses is small
c.A drug with a low therapeutic index has a narrow margin of safety,meaning that the difference between its toxic and therapeutic doses is small
d.Therapeutic index affects pharmacodynamics by determining the margin of safety between the toxic and therapeutic doses of a drug
A nurse is preparing to administer a medication that acts as an allosteric modulator.What does this mean?
Explanation
An allosteric modulator is a medication that binds to a specific receptor at a site different from the binding site for endogenous ligands.Allosteric modulators can affect receptor activity by enhancing or inhibiting the binding or activity of endogenous ligands.
a.An allosteric modulator binds to a different site from endogenous ligands,not the same site.
c.An allosteric modulator affects receptor activity indirectly by enhancing or inhibiting the binding or activity of endogenous ligands.
d.Allosteric modulation affects pharmacodynamics by altering receptor activity through indirect mechanisms.
A nurse is preparing to administer two medications with antagonistic effects.What should be considered when administering these drugs?
Explanation
Antagonistic effects occur when two drugs produce opposing effects and their combined effect is less than the sum of their individual effects.When administering two drugs with antagonistic effects,the nurse should consider their combined effect and adjust dosing accordingly.
a.Antagonistic effects occur when two drugs produce opposing effects and their combined effect is less than the sum of their individual effects.
c.Antagonistic effects occur when two drugs produce opposing effects and their combined effect is less than the sum of their individual effects.
d.Antagonistic effects affect pharmacodynamics by determining how two drugs interact when given together.
A nurse is preparing to administer a medication that acts as an inverse agonist.What does this mean?
Explanation
An inverse agonist is a medication that binds to a specific receptor and decreases its activity below basal levels.Inverse agonists can inhibit constitutive activity of receptors,producing an effect opposite to that of agonists.
a.An inverse agonist decreases,not increases,receptor activity below basal levels.
c.An inverse agonist decreases receptor activity below basal levels,not having no effect on receptor activity.
d.Inverse agonism affects pharmacodynamics by decreasing receptor activity below basal levels.
More questions on this topic
A nurse is preparing to administer a medication that acts as an agonist at a specific receptor. What effect will this medication have?
Explanation
An agonist is a medication that binds to a specific receptor and activates it, increasing its activity. A medication that acts as an agonist at a specific receptor will increase the activity of that receptor.
b. An agonist increases, not decreases, the activity of the receptor it binds to.
c. An agonist has an effect on the activity of the receptor it binds to by increasing its activity. d. An agonist activates, not blocks, the activity of the receptor it binds to.
A nurse is preparing to administer a medication that undergoes extensive first-pass metabolism. What route of administration should be used?
Explanation
First-pass metabolism refers to the metabolism of a drug by the liver before it reaches systemic circulation. Drugs that undergo extensive first-pass metabolism have a lower bioavailability when administered orally because a significant portion of the drug is metabolized before it reaches systemic circulation. Intravenous administration bypasses first-pass metabolism and delivers the drug directly into systemic circulation.
a. Oral administration would result in lower bioavailability due to first-pass metabolism.
c. Subcutaneous administration may also be subject to first-pass metabolism.
d. Intramuscular administration may also be subject to first-pass metabolism.
A nurse is preparing to administer a medication that acts as an antagonist at a specific receptor. What effect will this medication have?
Explanation
An antagonist is a medication that binds to a specific receptor and blocks its activation, preventing other medications or endogenous ligands from activating it. A medication that acts as an antagonist at a specific receptor will block the activity of that receptor.
a. An antagonist blocks, not increases, the activity of the receptor it binds to.
b. An antagonist does not directly decrease the activity of the receptor it binds to but prevents its activation by other medications or endogenous ligands.
c. An antagonist has an effect on the activity of the receptor it binds to by blocking its activation.
A nurse is preparing to administer two medications with additive effects.What should be considered when administering these drugs?
Explanation
Additive effects occur when two drugs produce similar effects and their combined effect is equal to sum of their individual effects.When administering two drugs with additive effects,the nurse should consider their combined effect and adjust dosing accordingly.
a.Additive effects occur when two drugs produce similar effects and their combined effect is equal to sum of their individual effects
b.Additive effects occur when two drugs produce similar effects and their combined effect is equal to sum of their individual effects
d.Additive effects affect pharmacodynamics by determining how two drugs interact when given together
A nurse is preparing to administer a medication that has high intrinsic efficacy.What does this mean?
Explanation
Intrinsic efficacy refers to how well a drug activates receptors once bound.A drug with high intrinsic efficacy produces maximal response when bound and can activate receptors fully.
b.A drug with high intrinsic efficacy produces maximal response when bound and can activate receptors fully
c.A drug with high intrinsic efficacy produces maximal response when bound and can activate receptors fully
d.Intrinsic efficacy affects pharmacodynamics by determining how well a drug activates receptors once bound
A nurse is preparing to administer two medications with synergistic effects.What should be considered when administering these drugs?
Explanation
Synergistic effects occur when two drugs produce similar or complementary effects and their combined effect is greater than the sum of their individual effects.When administering two drugs with synergistic effects,the nurse should consider their combined effect and adjust dosing accordingly.
b.Synergistic effects occur when two drugs produce similar or complementary effects and their combined effect is greater than the sum of their individual effects
c.Synergistic effects occur when two drugs produce similar or complementary effects and their combined effect is greater than the sum of their individual effects
d.Synergistic effects affect pharmacodynamics by determining how two drugs interact when given together
A nurse is preparing to administer a medication that has a low therapeutic index.What should be considered when administering this drug?
Explanation
Therapeutic index refers to the ratio between the toxic dose and the therapeutic dose of a drug.A drug with a low therapeutic index has a narrow margin of safety,meaning that the difference between its toxic and therapeutic doses is small.When administering a drug with a low therapeutic index,the nurse should carefully monitor the client for signs of toxicity.
a.A drug with a low therapeutic index has a narrow margin of safety,meaning that the difference between its toxic and therapeutic doses is small
c.A drug with a low therapeutic index has a narrow margin of safety,meaning that the difference between its toxic and therapeutic doses is small
d.Therapeutic index affects pharmacodynamics by determining the margin of safety between the toxic and therapeutic doses of a drug
A nurse is preparing to administer a medication that acts as an allosteric modulator.What does this mean?
Explanation
An allosteric modulator is a medication that binds to a specific receptor at a site different from the binding site for endogenous ligands.Allosteric modulators can affect receptor activity by enhancing or inhibiting the binding or activity of endogenous ligands.
a.An allosteric modulator binds to a different site from endogenous ligands,not the same site.
c.An allosteric modulator affects receptor activity indirectly by enhancing or inhibiting the binding or activity of endogenous ligands.
d.Allosteric modulation affects pharmacodynamics by altering receptor activity through indirect mechanisms.
A nurse is preparing to administer two medications with antagonistic effects.What should be considered when administering these drugs?
Explanation
Antagonistic effects occur when two drugs produce opposing effects and their combined effect is less than the sum of their individual effects.When administering two drugs with antagonistic effects,the nurse should consider their combined effect and adjust dosing accordingly.
a.Antagonistic effects occur when two drugs produce opposing effects and their combined effect is less than the sum of their individual effects.
c.Antagonistic effects occur when two drugs produce opposing effects and their combined effect is less than the sum of their individual effects.
d.Antagonistic effects affect pharmacodynamics by determining how two drugs interact when given together.
A nurse is preparing to administer a medication that undergoes extensive first-pass metabolism. What route of administration should be used?
Explanation
First-pass metabolism refers to the metabolism of a drug by the liver before it reaches systemic circulation. Drugs that undergo extensive first-pass metabolism have a lower bioavailability when administered orally because a significant portion of the drug is metabolized before it reaches systemic circulation. Intravenous administration bypasses first-pass metabolism and delivers the drug directly into systemic circulation.
a. Oral administration would result in lower bioavailability due to first-pass metabolism.
c. Subcutaneous administration may also be subject to first-pass metabolism.
d. Intramuscular administration may also be subject to first-pass metabolism.
Exams on Pharmacokinetics and pharmacodynamics
Custom Exams
Login to Create a Quiz
Click here to loginPharmacokinetics & Pharmacodynamics - 1
Lessons
Naxlex
Just Now
Login to View Pharmacokinetics and pharmacodynamics Study Video
Notes Highlighting is available once you sign in. Login Here.
Objectives
- Understand the fundamental principles of pharmacokinetics, including drug absorption, distribution, metabolism, and elimination, and how these processes influence drug concentration in the body.
- Identify factors that can alter drug pharmacokinetics, such as age, genetics, liver function, kidney function, and drug-drug interactions, and recognize the implications of these alterations on drug therapy.
- Describe the concept of pharmacodynamics and how drugs exert their effects on target cells or receptors, including agonists, antagonists, and enzyme inhibitors.
- Analyze the relationship between drug dosage, drug response, and therapeutic outcomes to optimize drug therapy and minimize adverse effects.
- Apply knowledge of pharmacokinetics and pharmacodynamics to individualize drug dosing regimens for specific patient populations, such as pediatric, geriatric, and pregnant patients, considering their unique physiological characteristics and needs.
- Pharmacokinetics and pharmacodynamics are essential concepts in the field of nursing and pharmacology.
Pharmacokinetics
Pharmacokinetics refers to the study of how the body processes drugs, including their absorption, distribution, metabolism, and elimination. These processes determine the concentration of a drug at its site of action and its overall effect on the body.
Absorption
- Absorption is the process by which a drug enters the bloodstream from its site of administration.
- Factors influencing drug absorption include route of administration, drug formulation, blood flow to the site of administration, and drug solubility.
- Oral administration is the most common route and can be influenced by pH levels, food interactions, and the first-pass effect.
- Other routes of administration include sublingual, buccal, inhalation, topical, transdermal, intravenous, intramuscular, and subcutaneous.
Distribution
- Distribution involves the transport of a drug from the bloodstream to its site of action.
- Factors influencing drug distribution include blood flow, drug solubility, drug-protein binding, and tissue permeability.
- Drugs can bind to plasma proteins, primarily albumin, and may be displaced by other drugs, leading to increased free drug concentration.
- Lipid-soluble drugs can penetrate cell membranes more easily and distribute throughout the body more readily.
Metabolism (Biotransformation)
- Metabolism refers to the enzymatic conversion of a drug into metabolites that are more easily eliminated from the body.
- The liver is the primary site of drug metabolism, although other organs such as the kidneys and intestines also play a role.
- The main enzyme system responsible for drug metabolism is the cytochrome P450 system.
- Drug metabolism can lead to active or inactive metabolites, and genetic variations in drug-metabolizing enzymes can affect drug responses.
- Factors influencing drug metabolism include age, liver function, and drug-drug interactions.
Elimination (Excretion)
- Elimination is the process by which drugs and their metabolites are removed from the body.
- The primary route of drug elimination is through the kidneys via urine (renal excretion).
- Other routes of drug elimination include faeces (biliary excretion), lungs (exhalation), sweat, and breast milk.
- Renal excretion is influenced by glomerular filtration, passive tubular reabsorption, active tubular secretion, and renal blood flow.
- Clearance is a measure of the rate at which a drug is eliminated from the body and is influenced by factors such as renal function and drug half-life.
Additional Concepts
- Half-life: The half-life of a drug is the time it takes for the plasma concentration of the drug to decrease by half. It determines dosing frequency and helps estimate the time it takes for a drug to reach a steady-state concentration.
- Bioavailability: Bioavailability refers to the fraction of an administered dose of a drug that reaches the systemic circulation. It is influenced by the route of administration and the extent of drug metabolism and can vary between different drug formulations.
- First-pass effect: The first-pass effect occurs when drugs administered orally are extensively metabolized by the liver before reaching the systemic circulation. This can significantly alter the bioavailability of the drug.
- Drug-drug interactions: Drug-drug interactions occur when one drug affects the pharmacokinetics of another drug, leading to altered drug concentrations and potential therapeutic or adverse effects. Common mechanisms include enzyme inhibition or induction, alteration of protein binding, and changes in renal excretion.
Pharmacodynamics
Pharmacodynamics refers to the study of how drugs exert their effects on the body. It involves the interaction between drugs and their target receptors or cellular processes.
Receptor Interactions
- Most drugs exert their effects by binding to specific receptors in the body.
- Drug-receptor interactions can be agonistic (activating the receptor) or antagonistic (inhibiting the receptor).
- Agonists can have full or partial agonistic effects, while antagonists can be competitive or non-competitive.
- Affinity refers to the strength of binding between a drug and its receptor, while efficacy refers to the ability of a drug to produce a pharmacological response.
Dose-Response Relationship
- The dose-response relationship describes the relationship between the dose of a drug and its effects on the body.
- The minimum effective concentration (MEC) is the plasma drug level required to produce a therapeutic effect.
- The toxic concentration is the plasma drug level at which adverse effects occur.
- The therapeutic range is the plasma drug concentration between the MEC and the toxic concentration, where therapeutic effects are achieved without toxicity.
Therapeutic Index
- The therapeutic index (TI) is a measure of a drug's safety margin and is calculated as the ratio between the toxic dose and the therapeutic dose.
- A high therapeutic index indicates a wide margin of safety, while a low therapeutic index indicates a narrow margin of safety.
- Drugs with a narrow therapeutic index require careful monitoring of drug concentrations to prevent toxicity.
Time-Effect Relationships
- Drugs can exhibit different time-effect relationships, including immediate onset, delayed onset, peak effect, and duration of action.
- Onset of action refers to the time it takes for a drug to start producing a therapeutic effect.
- Peak effect is the time at which a drug produces its maximum therapeutic effect.
- Duration of action is the length of time a drug produces its therapeutic effect before it is eliminated from the body.
Drug-Drug Interactions
- Drug-drug interactions occur when one drug affects the pharmacodynamics of another drug, leading to altered therapeutic or adverse effects.
- Drug interactions can occur at the receptor level, affecting drug binding or response, or at the cellular level, affecting drug metabolism or transport.
- Some drug interactions can result in potentiation (increased effects), antagonism (decreased effects), or adverse reactions.
Individual Variations
- Individual variations in pharmacodynamics can occur due to genetic factors, age, body weight, gender, and other patient-specific characteristics.
- Genetic polymorphisms in drug receptors or enzymes can affect drug response and metabolism.
- Age-related changes in receptor sensitivity and drug metabolism can impact drug effectiveness and safety.
Naxlex
Videos
Login to View Video
Click here to loginTake Notes on Pharmacokinetics and pharmacodynamics
This filled cannot be empty
Join Naxlex Nursing for nursing questions & guides! Sign Up Now
