Pharmacology: Pharmacodynamics Flashcards
what the body does to the drug is known as?
Pharmacokinetics
Explanation of the relationship between the dose you administer and the drugs plasma concentration over time is known as?
pharmacokinetics
Pharmacokinetics relationship is affected by what four variables?
absorption
distribution
metabolism
elimination
Does plasma concentration always correlate to clinical effect?
No
Biophase is also known as?
effect site
What determines the clinical effect of a drug?
The drug concentration in biophase (not plasma)
What the drug does to the body represents what?
Pharmacodynamics
Pharmacodynamics describes the relationship between what two things?
effect site concentration and the clinical effect
Units PK and PD by examining the relationship between plasma concentration and effect site concentration, is known as?
Pharmacobiophasics
What does the dose response curve illustrate?
relationship between the drug dose and its clinical effects.
It tells us about potency, efficacy, and slope
Where is potency represented on the dose response curve?
x-axis
dose required to achieve a given clinical effect is known as?
Potency
What affects potency?
absorption distribution metabolism elimination receptor affinity
What are measures of potency? (2)
ED50
ED90
What causes a left shift on the dose response curve?
increased affinity for the receptor
HIGHER POTENCY
lower dose required
increased affinity for the receptor leading to a higher potency and ultimately a lower dose required
What cause a right shift on the dose response curve?
decreased affinity for the receptor
lower potency
higher dose required
decreased affinity for the receptor leads to a lower potency and a higher dose is then required
explain efficacy, what does it measure?
efficacy is a measure of the intrinsic ability of a drug to elicit a given clinical effect
Where is efficacy represented on the dose response curve?
The y axis represents efficacy, it is the height of the plateau
Once the plateau phase is reached (max efficacy) for a given drug, what will giving more drug do?
More drug administration once plateau phase is reached (efficacy) will increase the risk of toxicity.
It will NOT produce additional effect.
What does the slope of a drug on the dose response curve tell you?
The slope tells us how many of the receptors must be occupied to elicit a clinical effect
What does a steep slope on the dose response curve tell you?
A steep slope implies that most of the receptors must be occupied before we observe the clinical response.
Name two types of drugs that have steep slopes?
NMB and inhaled anesthetics
How would you learn about individual variability of each patient?
compare the dose response curves from multiple patients
A drug that binds to a receptor follows the law of what?
Mass action
Different drugs may produce the same clinical effect but each drug requires a diff. dose to do so, this is a difference in what?
potency
Continuous administration of an agonist may cause what to occur at the target receptor?
down-regulation
What type of agonist is norepinephrine and at what receptor?
full agonist at the beta receptor
dopamine, propofol, and alfentanil are all examples of what type of agonist?
Full agonist
Instructs the receptor to produce its maximal response, mimics an endogenous ligand, binds to a receptor and turns on a specific cellular response, what am I?
Full agonist
binds to a receptor but is only capable of partially turning on a cellular response?
partial agonist
less efficacious than a full agonist and also sometimes called an agonist - antagonist?
partial agonist
What happens if you give a partial agonist opioid to an opioid addict, and why?
giving a partial agonist opioid to an opioid addict can precipitate withdrawal bc the partial agonist can block the effects of the agonist by competing for binding sites.
Nalbuphine is an example of a?
partial agonist
there is a ceiling to its efficacy
How does an antagonist work?
sits in the receptor and prevents the agonist from binding to it, it does not tell the cell to do anything
What type of drug occupies a receptor but does not have efficacy?
antagonist
cont. administration of what may cause up regulation of the target receptor?
antagonist
Which type of antagonism is reversible and which type is not reversible?
competitive antagonism is reversible
noncompetitive antagonism is NOT reversible
If a patient receives a competitive antagonist, the dose response curve for the agonist shifts which way?
shifts to the right
can an agonist overcome a competitive antagonism?
If so, how and what happens to the dose response curve?
Increasing the concentration of the agonist can overcome competitive antagonism. The agonist can achieve the same efficacy, BUT since more drug is required to achieve the desired clinical effect, the dose response curve would reflect a reduction in potency.
What does Rocuronium compete with at the neuromuscular junction?
Ach
Examples of competitive antagonist? (3)
Rocuronium
atropine
vecuronium
Explain to me what a noncompetitive antagonist does?
permanently binds to a receptor (covalent bond usually) and the effect can not be overcome by increasing the concentration of an agonist.
If you give a noncompetitive antagonist what does the dose response curve do?
The dose response curve for the agonist is shifted down, so that it resembles a partial agonist
What is the only thing that can reverse the effects of a noncompetitive antagonist?
producing new receptors
long duration of action for these drugs
Example of a noncompetitive antagonist?
ASA
inhibits COX-1 enzyme for the entire life of the platelet
