Flashcards in Primer 10 Deck (12):

1

## What are the symptoms of excess parasympathetic activation? Parasympathetic inactivation?

###
SLUDE BBB/ DUMBELLS excess

opposite effects for inactivation

2

## What drug reverses organophosphate poisoning?

### pralidoxime

3

##
What is "Vmax" in kinetics? Where would you find it on a velocity/ concentration (curved) graph?

Where would you find it on a linear graph?

###
-V max is the highest reaction velocity that can be achieved with a given amount of enzyme.

-Point at which the addition of substrate cannot increase the reaction speed because all enzymes are saturated.

-Point at which zero order kinetics is observed.

*1/Vmax is the y intercept on a linear graph, and the highest velocity achieved on a curved plot.

4

##
What is "Km" in kinetics? Where would you find it on a velocity/ concentration (curved) graph?

Where would you find it on a linear graph?

###
-Km is the amount of substrate needed to reach half of a reactions maximum velocity

-It is representative of an enzymes affinity for a substrate. Low Km = high affinity because less substrate is needed to reach max reaction speed.

*1/-Km is the x intercept of a linear plot, and the [S] at 1/2Vmax on a curved plot.

5

## How does the addition of a competitive inhibitor effect Vmax/ Km?

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-Competitive inhibitors can be overcome by the addition of substrate and therefore do not change Vmax.

-With the addition of a competitive inhibitor, only Km is increased (representing a decreased affinity due to blockage of the enzymes active site)

-No change Vmax, increase Km

6

## How does the addition of a noncompetitive inhibitor effect Vmax/ Km?

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-Noncompetitive inhibitors irreversibly inactivate enzymes. They cannot be overcome by the addition of a substrate and therefore decrease Vmax.

-Because they do not bind the active site of an enzyme, they do NOT change Km.

-Noncompetitive: decrease in Vmax, no change Km

7

##
PRACTICE THE CONCEPT-

On a linear enzyme kinetics plot, how would a decrease in enzyme affinity appear?

What causes a decrease in enzyme affinity?

*Note: linear plot = 1/V0 vs 1/Km (y vs x)

###
-decreased enzyme affinity= increased Km.

-Would appear as a RIGHT shift of a linear plot.

-caused by addition of a competitive inhibitor; would not be accompanied by a change in Vmax/ y intercept.

8

## Volume of distribution equation for a drug that is administered IV (100% bioavailable):

###
Vd= drug dose/ drug concentration

9

## Equation for drug clearance:

###
CL= elimination/ concentration

CL= K x Vd where K = 0.7/ t1/2

Therefore...... CL= (0.7 x Vd)/ t1/2

10

## Loading Dose Equation:

###
LD= Css x Vd / F

where F = bioavailability and can be disregarded for IV medications.

11

## Maintenance Dose Equation:

### MD= Css x CL

12