Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/52

Click to flip

52 Cards in this Set

  • Front
  • Back
Km: Definition
Km = Substrate at 0.5*Vmax
Km reflects the affinity of the enzyme for its substrate
Vmax indicates what?
Vmax is directly proportional to the enzyme concentration.
Relationship between Km and affinity
-The lower the Km, the higher the affinity
-Smaller Km means enzyme is saturated earlier, which means that small amounts of substrate are picked up by the enzyme.
Reading an inverse curve: Y-intercept equals ?
1/Vmax
The higher the Y-intercept the lower the Vmax
Reading an inverse curve: X-intercept equals ?
(1/-Km)
The further to the right the x-intercept, the greater the Km
Reading an inverse curve: Slope equals ?
Km/Vmax
Reading an inverse curve: Effect of a competitive inhibitor
X-intercept farther to the right, meaning Km is greater, because you need more substrate to get the same effect as the competitive inhibitor is hogging the enzyme.

The y-intercept is the same, meaning Vmax hasn't changed, because there isn't any more enzyme.


The slope is greater, because Km has increased while Vmax has stayed the same.
Reading an inverse curve: Effect of a noncompetitive inhibitor
The x-intercept is the same, meaning Km is the same, because the affinity for the enzyme hasn't changed, there's just less of it.


The y intercept has increased, meaning Vmax has decreased, because enzyme has been inactivated by the noncompetitive inhibitor

The slope is greater, because Vmax has decreased while Km has stayed the same.
Competitive inhibitor: Resemble substrate
Yes
Competitive inhibitor: Overcome by increased substrate?
Yes
Competitive inhibitor: Binds active site?
Yes
Competitive inhibitor: Effect on Vmax
Unchanged. The amount of enzyme has not changed.
Competitive inhibitor: Effect on Km
Increased. A lot more substrate needs to be available to seize the active sites.
Noncompetitive inhibitor: Resemble substrate?
No
Noncompetitive inhibitor: Overcome by increased substrate?
No
Noncompetitive inhibitor: Binds active site?
No
Noncompetitive inhibitor: Effect on Vmax
Decreased. Takes the enzyme out.
Noncompetitive inhibitor: Effect on Km
Unchanged. Does not change the affinity for the enzyme.
Volume of distribution: Abbreviation
Vd
Vd: Stands for what?
Volume of distribution
Volume of distribution: definition
Vd = (amount of drug in the body)/(plasma drug concentration)
Volume of distribution: What alters it?
Liver and kidney disease
Where are drugs with a low Vd distributed?
plasma
Where are drugs with a medium Vd distributed?
extracellular space
Where are drugs with a high Vd distributed?
tissues
Clearance: definition
=(rate of elimination of drug)/(plasma drug concentration)

=Vd x Ke where Ke=elimination constant
Half life: definition
The time required to change the amount of drug in the body by 1/2 during elimination (or during a constant infusion).
What percentage of steady state is a drug at after: 1 half life
50%
What percentage of steady state is a drug at after: 2 half lives
75%
What percentage of steady state is a drug at after: 3 half lives
87.5%
What percentage of steady state is a drug at after: 3.3 half lives
90%
What percentage of steady state is a drug at after: 4 half lives
94%
How many half lives does it take for a drug to reach the following percentage of steady state: 50%
1 half life
How many half lives does it take for a drug to reach the following percentage of steady state: 75%
2 half lives
How many half lives does it take for a drug to reach the following percentage of steady state: 87.5%
3 half lives
How many half lives does it take for a drug to reach the following percentage of steady state: 90%
3.3 half lives
How many half lives does it take for a drug to reach the following percentage of steady state: 94%
4 half lives
Cp stands for what?
target plasma concentration
What is the abbreviation for target plasma concentration?
Cp
In pharmacology, what is F an abbreviation for?
Bioavailability
What is the abbreviation in pharmacology for bioavailability?
F
Loading dose: Definition
Loading dose = (Cp * Vd)/F (where Cp equals the target plasma concentration, Vd equals volume of distribution, and F equals bioavailability)
Maintenance dose: Definition
Maintenance dose = (Cp * CL)/F (where Cp is the target plasma concentration and CL is clearance and F is bioavailability)
Zero-order elimination: definition
Constant elimination over time regardless of drug.
How does Cp vary with time during zero-order elimination?
Cp decreases linearly with time.
Zero-order elimination: Drug examples
-Ethanol
-Phenytoin
-Aspirin (at high concentrations)
First-order elimination: definition
Rate of elimination is proportional to drug concentration
Zero-order elimination vs First-order elimination: Comparison
Zero-order: Constant amount of drug eliminated per unit time

1st-order: Constant fraction of drug eliminated per unit time
How does Cp vary with time during first-order elimination?
Cp decreases exponentially with time.
Urine: Which species get trapped in urine?
Ionized species
In what kind of environment is the following trapped?: Weak acids
Basic environments
In what kind of environment is the following trapped?: Weak bases
Acidic environments