Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
What is the difference between a dose-response curve and an agonist concentration curve?
|
The agonist concentration curve shows the effect of some drug concentration in the body; the Dose-response curve shows the effect of a Dose on the body, based on how much it is absorbed by an individual
|
|
|
What is required for a dose response curve to mirror a concentration-effect curve?
|
The dose response curve has to be ideal - with minimal factors intervening between the site of drug administration and its ultimate site of action.
|
|
|
What are the 4 main factors that can intervene between the site of drug administration and its ultimate site of action?
|
Absorption
Distribution Metabolism Excretion |
|
|
What are 3 pieces of information we get from a dose-response curve?
|
-Maximum effect (efficacy)
-ED50 value -Potency |
|
|
What is ED50?
|
The dose of drug that achieves 50% of its maximum effect
|
|
|
How is potency illustrated?
|
By the position of the curve on the x-axis; the lower it is, the more potent the drug is.
|
|
|
What is Potency?
|
The relationship between the amount of drug administered and its effect.
|
|
|
What is Potency related to inversely?
|
ED50
|
|
|
What are the 2 main determinants of Potency?
|
1. Affinity for the site of action
2. Ability to reach the site of action |
|
|
What is Efficacy?
|
The maximal effect that is produced by a dose of a drug
|
|
|
How is Efficacy illustrated on the dose-response curve?
|
By the Y-axis
|
|
|
So on the dose-response curve,
-X-axis illustrates: -Y-axis illustrates: |
X = potency
Y = efficacy |
|
|
What are the 3 determinants of efficacy?
|
1. Intrinsic activity
2. Characteristics of the effector 3. Limitations on how much drug can be administered d/t side effects |
|
|
What is the idealized shape of a dose-response curve?
|
Perfectly S-shaped with an effect that goes from 0-100% over 3 log units.
|
|
|
What is the only case in which the shape of the dose-response curve really would be ideal?
|
If the only determinant were binding of the drug to receptor
|
|
|
And what is binding of drug to its receptor dependent upon?
|
The law of mass action
|
|
|
What are 3 things that cause the dose-response curve to deviate?
|
1. Additive effects of the drug
2. Threshold effects 3. Antagonist effects |
|
|
Why do we care about the shape of the dose-response curve?
|
Because it has therapeutic implications and impacts the ease of drug use.
|
|
|
What is an example of an antagonist effect that causes deviation in the shape of the dose-response curve?
|
Increasing concentration of the drug resulting in reduced efficacy - the curve becomes U-shaped upside down.
|
|
|
What type of dose-response curve shape means the drug is very difficult to use? Why?
|
When it is steep - because the range between beneficial and toxic effects may be very narrow.
|
|
|
Do physicians often determine dose-response curves in individual patients?
|
Rarely
|
|
|
What is the difference between a graded dose-response curve and a quantel dose-response curve?
|
Graded = a curve for an individual patient
Quantel = a curve of the overall responses of a population of patients |
|
|
What does the dose-response relationship that is quantel give us an idea of?
|
The overall responses of a population of patients to drug doses.
|
|
|
What type of distribution do most drug effects follow for a population?
|
Log-normal distribution
|
|
|
What % of the population has the highest frequency of response to the drug within 1 SD on either side of the mean ED50?
|
68%
|
|
|
What % of the population has a response to the drug within 2 SD on either side of the mean ED50?
|
95%
|
|
|
What does ED50 refer to for a quantel dose-response curve?
|
The dose of drug that shows a positive response in 50% of the population being surveyed.
|
|
|
What type of distribution is a quantel dose-response curve most often depicted as?
|
Cumulative frequency distribution
|
|
|
What are 4 reasons for variation in response among individuals to a given drug?
|
1. Differences in pharmacokinetics
2. Variation in the amount of endogenous agonist 3. Changes in the number or function of target 4. Differences in a component distal to the target |
|
|
Example of differences in pharmacokinetics:
|
Smoking induces metabolism of many drugs
|
|
|
Example of variation in the amount of endogenous agonist:
|
Athletes have low levels of NE; giving propanolol to block alpha receptors will cause a much stronger reduction in heartrate than in patients with high amts of NE
|
|
|
Example of changes in the number or function of target:
|
Tolerance to barbiturates
|
|
|
5 particular types of biological variability of responses to drugs in patients:
|
1. Idiosyncratic drug response
2. Hypo/hyper-reactiveness 3. Hypersensitivity 4. Tolerance 5. Tachyphylaxis |
|
|
What is an idiosyncratic drug response?
|
An unexpected/unexplainable response based upon the mechanism.
|
|
|
Where will patients that are hypo or hyper-reactive to a drug show up?
|
On the tail ends of the log-normal frequency distribution.
|
|
|
What is drug hypersensitivity?
|
An allergic or inflammatory response to a drug
|
|
|
What is tolerance?
|
Slowly developing resistance to a drug following repeated exposure to the drug.
|
|
|
What is rapidly developing resistance to a drug called?
|
Tachyphylaxis
|
|
|
What is a quantel dose response curve?
|
The cumulative frequency relationship between drug dose and population response
|
|
|
What is the Y-axis on the cumulative frequency distribution of drug dose and population response?
|
The quantel measure of response or effect - all or none.
|
|
|
What are 3 effects/responses that can be measured? What 3 things can we obtain then?
|
Effect - ED50
Toxicity - TD50 Lethality - LD50 |
|
|
What is the Therapeutic index?
|
The ratio of TD50/ED50
|
|
|
What type of therapeutic index is preferable?
|
Larger - that means the TD50 is farther from the ED50 and it's easier to give to a population
|
|
|
What does the shape of the curve of the quantel dose response curve represent?
|
The variability in response in the population
|
|
|
What type of curve for the quantel dose-response curve is easier to use?
|
Steeper - means there's less variability in response
|
