Pharmacodynamics: Drug Action Overview

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Questions and Answers

What is the primary role of a noncompetitive antagonist in drug action?

To enhance the effects of an agonist drug

To directly stimulate receptor sites for increased response

To prevent another chemical from reacting with a different receptor site on the same cell (correct)

To bind to the same receptor site as the agonist and block it

Which parameter of drug action describes the time it takes for the drug to show its first effect?

Onset of Action (correct)

Action Interval

Duration of Action

Peak Action

What best describes the 'peak action' of a drug?

The duration the drug is effective

The highest concentration of drug in the blood (correct)

The time the therapeutic effects are first noticed

The time when the drug is administered

What is a predictable adverse effect of a drug?

Excessive pharmacologic effects Signup and view all the answers

How do ACE inhibitors function in relation to enzymes?

By protecting target cells from the action of certain enzymes Signup and view all the answers

What is an example of an effect drugs can have besides the intended therapeutic effect?

Inducing undesirable or unpleasant responses Signup and view all the answers

What characterizes a competitive antagonist?

It binds to the same receptor site as the agonist Signup and view all the answers

What can lead to toxic effects from drugs?

Overuse or underuse of the drug Signup and view all the answers

What is the classification of drugs that have a high potential for abuse but also have currently accepted medical uses in the United States?

Schedule II Signup and view all the answers

Which schedule of drugs is known for having the lowest potential for abuse among controlled substances?

Schedule V Signup and view all the answers

Which category indicates that adequate studies in pregnant women have not shown a risk to the fetus in the first trimester?

Category A Signup and view all the answers

What is the purpose of Phase IV studies in drug approval?

To continually evaluate the drug after it has been marketed Signup and view all the answers

Which of the following drugs is categorized as Schedule III?

Hydrocodone Signup and view all the answers

What consequence may result from the abuse of Schedule IV drugs compared to Schedule III drugs?

Limited physical or psychological dependence Signup and view all the answers

Which category signifies that animal studies have not demonstrated a risk to the fetus, but human studies have not been performed?

Category B Signup and view all the answers

What is required from prescribers after a drug receives FDA approval?

Reporting of adverse effects Signup and view all the answers

What is required before a drug can be distributed in interstate commerce according to the Federal Food, Drug and Cosmetic Act of 1938?

The drug must be shown to be safe. Signup and view all the answers

Which amendment required certain drugs to be labeled with a specific caution regarding dispensing without a prescription?

Durham-Humphrey Amendment Signup and view all the answers

What are the four categories into which drugs may be classified according to federal statutes?

Prescription drugs, over-the-counter drugs, investigational drugs, illicit drugs Signup and view all the answers

What does the U.S. Pharmacopeia (USP) establish as per the Controlled Substance Act of 1970?

The legal standards for drug strength, purity, and quality Signup and view all the answers

Which of the following statements about prescription drugs is true?

They require a New Drug Application before marketing. Signup and view all the answers

What is one requirement for drugs classified under the Controlled Substance Act?

They must be demonstrated to have high purity. Signup and view all the answers

Who can prescribe prescription drugs as part of their practice?

Health care providers, veterinarians, and dentists Signup and view all the answers

What role does animal testing play in drug approval?

It is necessary due to different biological reactions. Signup and view all the answers

What physiological change is most likely to contribute to an increased risk of drug toxicity in older adults?

Reduced glomerular filtration rate Signup and view all the answers

Which factor is NOT typically related to medication errors in older adults?

Increased physical activity Signup and view all the answers

How does age-related loss of muscle tone affect older adults in relation to medication?

It contributes to increased total body fat content. Signup and view all the answers

What is a potential consequence of decreased liver function in older adults?

Increased risk of hepatotoxicity Signup and view all the answers

What type of data is classified as objective data in the nursing assessment?

Medication history noted in charts Signup and view all the answers

Which of the following changes occurs in liver function as people age?

Decreased liver volume Signup and view all the answers

What impact does a reduced number of intact nephrons have on older adults?

Increased risk of nephrotoxicity Signup and view all the answers

Which assessment is essential for ensuring safe nursing practice in medication management for older adults?

Taking a comprehensive medication history Signup and view all the answers

What type of immune response is primarily mediated by immune complexes?

Type III hypersensitivity reactions Signup and view all the answers

What is the expected dosage adjustment for oral medication due to the first-pass effect?

Higher than the IV dose Signup and view all the answers

What is a common treatment intervention for mild drug-induced reactions?

Provide frequent skin care Signup and view all the answers

Which of the following is an example of a Type IV reaction?

Ampicillin-induced skin rash in mono Signup and view all the answers

In cases of severe drug allergy, which intervention is most appropriate?

Notify the prescriber immediately Signup and view all the answers

What is a significant symptom of stomatitis caused by drug toxicity?

Swollen and inflamed mucous membranes Signup and view all the answers

What reaction is classified as an anaphylactic reaction?

Immediate and severe respiratory distress Signup and view all the answers

What should be avoided during hypersensitivity reactions involving skin lesions?

Rubbing the affected area Signup and view all the answers

Study Notes

Pharmacodynamics: Drug Action and Effects

Pharmacodynamics studies how drugs alter normal physiological functions.
Therapeutic effects are the desired positive changes; antagonists bind to receptors, blocking agonists (e.g., alpha and beta-blockers).
Competitive antagonists compete for receptor sites; non-competitive antagonists prevent reactions at different receptor sites.

Parameters of Drug Action

Onset of action: time from administration to first effect.
Duration of action: time the drug exerts its effect.
Peak action: time of highest drug concentration.

Mechanisms of Drug Action

Drugs may produce therapeutic effects by interacting with cells or organs.
Enzyme interaction: drugs can inhibit or protect target cells from enzyme actions (e.g., ACE inhibitors).

Toxic Effects of Drugs

Adverse effects can be predictable (excessive pharmacological effects) or unpredictable (patient sensitivity, other drug-related responses).
Examples of adverse effects include hemolytic anemia, thrombocytopenia, and drug-induced lupus erythematosus.
Type III reactions (immune complex mediated) can cause inflammation, lymphadenopathy, and fever (serum sickness).
Type IV reactions (delayed hypersensitivity) are mediated by lymphocytes; example: ampicillin-induced rash in patients with mononucleosis.
Drug allergies involve antibody formation, causing immune responses upon re-exposure.
Anaphylactic reactions (Type I) trigger histamine release, causing immediate reactions like respiratory distress.

Interventions for Drug Reactions

Mild cases of skin lesions: frequent skin care, avoid irritants, antihistamines.
Severe cases: discontinue the drug and notify the prescriber; topical corticosteroids or emollients may be used.

Stomatitis

Inflammation of mucous membranes, possibly due to direct toxicity or drug deposition in capillaries. Example: antineoplastic drugs.
Assessment includes swollen gums, gingivitis, and glossitis.

Drug Classification and Legislation

The Controlled Substances Act of 1970 classified drugs based on abuse potential and regulated manufacturing and distribution.
The Federal Food, Drug, and Cosmetic Act of 1938 required drug safety before distribution.
The Durham-Humphrey Amendment (1952) classified drugs as prescription (legend) or nonprescription (OTC).
Drug categories include prescription, OTC, investigational, and illicit drugs.
New Drug Application (NDA) is required for marketing prescription drugs in the United States.
Phase III studies evaluate drugs and are reviewed by FDA committees.
Phase IV studies monitor post-marketing effects and adverse reactions are reported to the FDA.

Schedule of Controlled Substances

Schedule I: High abuse potential, no accepted medical use (e.g., heroin, LSD).
Schedule II: High abuse potential, accepted medical use (e.g., morphine, cocaine).
Schedule III: Lower abuse potential than I and II, accepted medical use (e.g., codeine with acetaminophen).
Schedule IV: Low abuse potential, limited physical/psychological dependence (e.g., diazepam).
Schedule V: Lowest abuse potential, limited quantities of narcotics (e.g., antitussives).

Pregnancy Categories for Drug Safety

Category A: No risk to the fetus.
Category B: Animal studies show no risk, human studies lacking.

Increased body fat, decreased muscle tone.
Decreased protein-binding capability.
Decreased enzyme levels and liver blood flow, leading to reduced metabolism.
Decreased glomerular filtration rate and number of nephrons, leading to reduced elimination.
Older adults are more susceptible to hepatotoxicity and drug toxicity due to accumulation.

Factors Contributing to Drug Problems in Older Adults

Sensory losses affecting medication management.
Memory loss affecting self-care.
Multiple pharmacies and healthcare providers increasing errors.
Increased number of drugs increasing medication errors.

Nursing Process in Pharmacology: Assessment

Data collection: subjective (patient reports) and objective (chart, lab results, physical assessment).
Medication history: current prescription and OTC agents.
Client understanding of illness.

Safe Nursing Practice

Obtain a thorough medication history.
Assess the patient's understanding of the illness and medication.

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Description

This quiz covers the key concepts in pharmacodynamics, focusing on how drugs affect physiological functions, the parameters of drug action, and mechanisms behind therapeutic effects. Understand the roles of antagonists and the impact of adverse effects on patient health. Test your knowledge of these fundamental principles of pharmacology.