Lehne Book: Chapter 5 - Pharmacodynamics Flashcards
The study of the biochemical and physiologic effects of drugs and the molecular mechanisms by which those effects are produced. Simply put, the study of what drugs do to the body and how they do it.
Pharmacodynamics
____-_____ ______ is the relationship between the size of an administered dose and the intensity of the response produced.
dose-response relationship
Is the dose-response relationship graded or all-or-nothing? what is the importance of this?
Graded, which gives us more control and allows us to fit the needs of the patient. If it were all-or-nothing, and could only produce one intensity of response, we could not treat various patients with that drug.
_____ _____ is defined as the largest effect that a drug can produce. It is indicated by the height of the dose-response curve.
Maximum Efficacy
T or F: A drug with very high maximal efficacy is more desirable than a drug with lower efficacy.
False, we want to match the intensity of the response to the patient’s needs. Ex. Furosemide can cause dehydration because it is a high efficacy diuretic. We may choose a lower efficacy to reduce the intensity of volume of water to be mobilized.
The term ______ refers to the amount of drug we must give to elicit an effect.
potency
If morphine produces pain relief at a lower dose than meperidine, is it more potent or less potent?
more potent
Drugs are chemicals that interact with chemicals inside the body. ________ are the special chemicals in the body to produce effects. It is any functional macromolecule in a cell to which a drug binds to to produce effects.
Receptors
The binding of drugs to receptors can either _____ or ____ the action of the body’s own regulatory molecules.
mimic (agonist) or block (antagonist)
T or F: Drugs produce their therapeutic effects by helping the body use its pre-existing capabilities. Drugs cannot give cells new functions.
True
There are four primary receptor families.
- Cell membrane embedded ______
- __ protein-coupled systems
- ligand-gated ____ channels
- transcription factors
- enzymes
- G
- ion
Transcription factors differ from other receptors in two ways. 1. They are found _____ the cell rather than _____ the cell. 2. Responses to activation of these receptors are _____ instead of _____.
p.52
- inside/within the cell rather than outside the membrane
- delayed versus instant, or within milliseconds.
Transcription factors are situated in the nucleus on the DNA; therefore, they can only be activated by ______ that are ______ soluble.
ligands; lipid
The more selective a drug is, the fewer side effects it will produce. Why is that?
Selective drug action is possible because drugs act through specific receptors. p.52
If drugs are selective for one receptor only, why does the drug still cause some side effects?
The receptor may be located in more than one area of the body, causing side effects.
_______ _______ Theory states that the intensity of response to a drug is proportional to the number of receptors occupied.
Simple Occupancy Theory
The strength of the attraction between a drug and its receptor.
Affinity
T or F: Drugs with high affinity (attraction to receptors) can bind when present in low concentrations. This means drugs with high affinity are potent.
True.
This term refers to the ability of a drug to activate a receptor upon binding. The higher this activity, the more intensely a receptor is activated.
intrinsic activity
Affinity is to potency as Intrinsic activity is to ______ _____.
Drugs with high intrinsic activity cause intense receptor activation, therefore intense responses.
maximal efficacy
T or F: Agonists are molecules that activate receptors. These molecules include neurotransmitters, hormones, other endogenous regulators as well as drugs that mimic them.
True
__________ produce their effects by preventing receptor activation by endogenous regulatory molecules and drugs.
antagonists
Affinity allows the agonist to bind to receptors. What does intrinsic activity allow?
Allows the bound agonist to activate or turn on the receptor function. p.54
T or F: If there is no agonist present, antagonist will still have an effect.
False. antagonist prevents agonist from activating receptor. If there is no activation, antagonist cannot deactivate.
Antagonist can be competitive or non-competitive. Non-competitive bind ________ to receptors. They reduce the maximal response an agonist can elicit.
irreversibly.
Because irreversible they are rarely used therapeutically.
Because competitive antagonists bind reversibly to receptors, the inhibition they cause is _________.
surmountable.
What causes down-regulation? Hint: Down-regulation is also referred to as desensitized or refractory.
When receptors of a cell are continually exposed to an agonist, the cell usually becomes less responsive.
What is interpatient variation?
The variation in response to a drug from patient to patient.
What is ED50?
The average effective dose.
What can a nurse do to address interpatient variability?
After initial dose, monitor and then fine tune. If there is not a great response after an ED50, discuss increasing the dose with a dr. In the case of pain meds, you must address the patient’s concern. Be cautious of the lethal dose!!!
