Pharmacokinetics and Pharmacodynamics I Flashcards Preview

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Flashcards in Pharmacokinetics and Pharmacodynamics I Deck (25)
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1

In the Michaelis-Menten equation, what is Km?

[S] at 1/2 of Vmax (p.226)

2

How does the value of Km relate to enzyme affinity for its substrate?

Higher Km means lower affinity; lower Km means higher affinity (p.226)

3

How does Vmax relate to enzyme concentration?

Vmax is directly proportional to enzyme concentration (p.226)

4

Describe the shape of the curve in an enzymatic reaction that follows Michaelis-Menten kinetics.

Hyperbolic curve (enzymatic reactions with positive cooperativity have a sigmoid curve) (p.226)

5

What does a Lineweaver-Burk Plot represent?

1/[S] vs 1/V (p.226)

6

What is the slope of the line in a Lineweaver-Burk plot?

slope= Km/Vmax (p.226)

7

What does the Y-intercept of a Lineweaver-Burk plot represent?

1/Vmax (p.226)

8

What is the relationship of the position of the Y intercept and Vmax in a Lineweaver-Burk plot?

The greater the Y intercept, the lower the Vmax (p.226)

9

What does the X-intercept of a Lineweaver-Burk plot represent?

=1/(-Km) (p.226)

10

What is the relationship of the position of the X intercept and Km in a Lineweaver-Burk plot?

The further to the right the X intercept (i.e. closer to the Y axis), the greater the value of Km and the lower the enzyme affinity (p.226)

11

In a Lineweaver-Burk plot, how do you distinguish a competitive inhibitor from a noncompetitive inhibitor?

Competitive inhibitors cross the line of the uninhibited reaction; non-competitive inhibitors do not cross the line (p.226)

12

Compare competitive and noncompetitive inhibitors in terms of the resemblance of the inhibitor to the substrate.

Competitive inhibitors resemble the substrate; non-competitive inhibitors do not (p.226)

13

Which types of enzymatic inhibitors can be overcome by increasing substrate and which ones can not?

Competitive inhibitors can be overcome by increasing [S]; non-competitive inhibitors can not (p.226)

14

Compare competitive and noncompetitive inhibitors in terms of binding to the active site.

Competitive inhibitors bind the active site; non-competitive inhibitors do not (p.226)

15

What is the effect of a noncompetitive inhibitor on Vmax?

Decreases Vmax (p.226)

16

What is the effect of a competitive inhibitor on Vmax?

No effect on Vmax (p.226)

17

What is the effect of a noncompetitive inhibitor on Km?

No change on Km (p.226)

18

What is the effect of a competitive inhibitor on Km?

Increases Km (p.226)

19

What pharmacodynamic property is primarily affected by competitive inhibitors?

Decreased potency (p.226)

20

What pharmacodynamic property is primarily affected by a non-competitive inhibitor?

Decreased efficacy (p.226)

21

What is bioavailability (F)?

The fraction of an administered drug that reaches systemic circulation unchanged (p.227)

22

What mode of drug delivery has 100% bioavailability?

IV dosing (p.227)

23

What is the volume of distribution of a drug?

A theoretical fluid volume required to maintain the total absorbed drug amount at the plasma concentration (p.227)

24

What conditions may alter the volume of distribution of plasma protein-bound drugs?

Liver and kidney disease may decrease protein binding and increase drug volume of distribution (p.227)

25

What is the equation for volume of distribution?

Vd= (amount of drug in the body)/ (plasma drug concentration) (p.227)