Pharmacodynamics and Adverse Effects Flashcards
What is pharmacodynamics?
The study of what drugs do to the body and how they do it
What is a therapeutic effect and why is that the goal?
It’s a positive change in a faulty physiological system
Why do we need to know pharmacodynamics?
We as nurses must be able to EDUCATE our patients, make PRN DECISIONS, be able to EVALUATE our patients and COMMUNICATE with prescribers
What determines the MEC of a drug?
The dose-response relationship
What determines the maximum response a drug can elicit?
The dose-response relationship
What determines toxic level
The dose-response relationship
What are you thinking about when you decide to increase the dosage to produce an increase in response?
The dose-response relationship
As a dose increases does the response increase or stay the same?
It increases
How do you find the desired intensity of response?
You start with a dose and change it up or down till you find the right amount
What is maximal efficacy?
The largest effect that a drug can produce (the peak)
What may happen if a drug’s maximal efficacy is very high?
It could become toxic
Why is the relative potency not an important characteristic?
Only important when a lack of potency forces inconveniently large doses
What are drugs?
Chemicals that produce effects by interacting with other chemicals
What are receptors?
Special chemicals in the body that most drugs interact with to produce effects
What does every cell have that receives a signal to elicit a response?
Receptors
What is a receptor?
A receptor is any functional macromolecule in a cell to which a drug binds to produce its effects
What do receptors normally receive signals from?
Hormones, neurotransmitters, and other regulatory molecules
What are the body’s normal points of control?
Receptors
Under physiologic conditions, what are receptors functions regulated by?
Molecules supplied by the body
What are the only two things drugs can do to the body?
Mimic or block the regulatory molevules
T/F Can drugs give cells new functions?
NO
What are receptor interactions?
The joining of the drug molecule with a receptor site on the surface of a cell or tissue
What is affinity?
The degree of attachment and binding, how much it wants the receptor
What are enzyme interactions?
Either inhibits or enhances the action of a specific enzyme
What is a nonselective interaction?
The drug does not interact with a receptor or enzyme
What is an agonist?
A drug that does the same action as an enzyme, there is a response
What is a partial agonist?
A drug that does the same thing as an enzyme but to a lesser extent
What is an antagonist?
A drug that blocks enzymes, there is no response
What are endogenous regulators (hormones) considered? Agonists or antiagonists?
Agonistis
Do adonists have affinity and intrinsic activity?
Yes and yes
Do antagonists have affinity and intrinsic activity?
Yes and no
Is morphine an agonist or antagonist?
Agonist
Is naloxone (Narcan) an agonist or antagonist?
Antagonist
What is the pharmacologic effect of an antagonist?
They prevent the activation of receptors by agonists
If there is no agonist will the antagonist have an observable effect?
No
What do noncompetitive antagonists do?
Bind IRREVERSITBLY, REDUCE the max response that an agonist can elicit (fewer receptor spots)
What do competitive antagonists do?
Bind REVERSIBLY, have equal affinity with agonists
Why is it that the more a cell tolerates a drug the less responsive it is?
The number of receptors on the cell surface and the sensitivity to agonists can change
When a drug binds to a receptor will it increase or decrease the rate of physiologic activity normally uncontrolled by that receptor?
Both
What do drugs use to help the body?
They use the body’s preexisting capabilities
Does the body have many similar receptors?
Yes
Will a drug have more or less side effects if it’s more selective?
Less
What will happen if a cell has continuous exposure to an agonist?
It will become desensitized and downregulate
What will happen is a cell has continuous exposure to an antagonist?
Hypersensitivity
What does it mean if a drug does not involve receptors?
It has simple physical or chemical interactions
What are some examples of receptorless drugs?
Antiacids, saline laxatives, chelating agents, antiseptics
Does the same dose work for every patient?
No there is interpatient variability due to different liver functions, kidneys, metabolism
What is the ED50?
Effective Dose for a population. The dose that is typically effective, the average starting point
What is the LD50?
The average lethal dose to 50% of animals treated
Is a drug safer if it has a higher or lower therapeutic index?
Higher, more space
What is a side effect?
Could be THERAPEUTIC, EXPECTED, DON’T HINDER the effect of the drug, MILD
What is an adverse effect?
Usually HARMFUL, HINDER the effect of the drug, more COMPLICATIONS, UNEXPECTED, SEVERE
What is a carcinogenic effect?
Causes cancer
What is an allergic reaction?
An immune response
What is a teratogenic effect?
Can cause birth defects
What is a QT interval interference?
Messes with the heart rhythm
What is ADR?
Adverse drug reactions
What are side effects?
unavoidable secondary effects at therapeutic doses
What is a side effect of morphine?
Makes you sleepy
What is toxicity?
ADR is caused by excessive dosing
What is an allergic reaction?
An immune response, mild to severe
What is an idiosyncratic effect?
A reaction completely unexpected, even opposite
What is a teratogenic effect?
Drugs capable of causing birth defects
What is a positive drug-drug interaction?
An intended and desired interaction between drugs
Why do patients take multiple different drugs?
To treat ONE disorder, MULTIPLE disorders, OVER-THE COUNTER drugs (caffeine, nicotine, alcohol)
What are the three possible consequences of drug-drug interactions?
Intensification, reduction, or unique response
What is an example of an intensification of therapeutic effects with drug-drug interactions?
Sulbactam and ampicillin- antibiotics, a synergistic effect
What is an example of increased adverse effects with drug-drug interactions?
Aspirin and warfarin- Blood thinners
What is an example of reduced effectiveness with drug-drug interactions?
Propranolol and albuterol- shrink airways and open airways (INHIBITORY)
What is an example of reduced adverse effects with drug-drug interactions?
Naloxone to treat morphine overdose
What is an example of a unique response to drug-drug interactions?
Alcohol with disulfiram- makes you vomit
What are the four basic mechanisms drugs can interact with?
DIRECT chemical or physical interaction, PHARMACOKINETIC, PHARMACODYNAMIC, combined TOXICITY
Your 80-year-old patient tells you they keep all of their pills in one container, what should you say?
They shouldn’t do that because they could chemically react with each other
Your pt has multiple IV lines, should you run them together?
Only after you establish compatibility
What is precipitation with IVs?
When it forms crystals
What are the four things that effect pharmacokinetic interactions?
Altered ABSORPTION, DISTRIBUTION, EXCRETION, METABOLISM
What drug elevates gastric pH?
Antacids
What drug alters absorption?
Laxatives
What drug depresses peristalsis?
Opioids
What drug induces vomiting?
Ipecac
What is an absorbent drug?
Activated charcoal
What causes altered distribution?
Competition for protein binding
When a drug is bound to a protein is it active or inactive?
Inactive
When you increase the dose is there more or less active drug
More
How does the risk for serious drug interaction relate to the number of drugs a patient is taking?
It’s directly proporitonate
Why is drug-drug interaction especially important for drugs with low therapeutic indices?
Because it’s easy to over dose
How can you minimize adverse drug-drug interactions?
MINIMIZE the number of drugs the pt takes, drug HISTORY, ILLICIT drug use, adjust the DOSE, or TIMING, MONITOR the pt
Does milk increase or decrease absorption for tetracycline?
Decrease
Does fiber increase or decrease the absorption of digoxin?
Decrease
Does high-calorie meals increase or decrease the absorption of saquinavir?
Increase
What does grapefruit juice do to drugs?
Inhibits the metabolism or raises the drug blood levels
What drugs are affected by the cheese effect?
MAOIs (antidepressants)
Should you have theophylline and caffeine?
No it could lead to drug toxicity
Should you have potassium-sparing diuretics and salt substitutes?
No, it could lead to drug toxicities
Should you have warfarin and foods rich in vitamin K?
No, warfarin is a blood thinner, and vitamin K aids in clotting
Can conventional drugs interact with herbal preparations?
Yes
What does St. John’s wort do?
Induces drug-metabolizing enzymes and reduces the blood levels of many drugs
If there is no previous exposure to a drug, how long can an allergic reaction wait to happen?
Several days as the body must make antibodies
What should you keep in mind as a nurse related to allergic reactions?
pt TEACHING, PREVENTION, EMERGENCY management, EPI
