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Flashcards in Pharm Basics Deck (36):
1

Km

The concentration at which the reaction is half of maximum. Lower the Km, the higher the affinity.

2

Michaelis-Menten Equation

Vmax*S/Km+S

3

Michaelis-Menten Equation

Vmax*S/Km+S

4

Lineweaver Burk Plot

Plots against 1/V and 1/s

5

X intercept on lineweaver burk?

-1/Km. The further to the right (closer to zero), the lower the affinity

6

Y intercept on lineweaver burk

1/Vmax.

7

Slope on lineweaver burk

Km/Vmax

8

Slope on lineweaver burk

Km/Vmax

9

Characteristics of a reversible competitive inhibitor

Resemble substate, overcome by increasing S, bind active site, DO NOT CHANGE VMAX, increase Km.

Decrease potency of an enzyme

10

Characteristics of an irreversible competitive inhibitor

Resemble substate, not overcome by increasing S, bind active site, decrease Vmax, don't change Km.

Decrease efficacy of an enzyme

11

Characteristics of an irreversible competitive inhibitor

Resemble substate, not overcome by increasing S, bind active site, decrease Vmax, don't change Km.

Decrease efficacy of an enzyme

12

Noncompetitive inhibitor characteristics

Don't resemble substrate, not overcome by increasing S, don't bind active site,

13

Bioavailability

Fraction of administered drug that reaches systemic circulation unchanged. IV dose, F=100. For oral dose, F

14

Volume of distribution equation

Amount of drug in the body/plasma drug concentration

15

Drugs with low Vd

Remain mostly in blood, these include large/charged molecules

16

Drugs with medium Vd

Mostly in EFC. Include small hydrophilic molecules

17

Drugs with large Vd

Mostly in tissues including fat. Small lipophilic molecules especially if bound to tissue protein

18

Half-life equation

(0.693 x Vd)/CL

19

How many half-lives does it take to reach steady state?

3.3 to reach 90%. 4 or 5 to reach full steady state.

20

Clearance equation

Rate of elimination of the drug/plasma drug concentration.

VdXke (elimination constant)

21

Loading dose

(Cp X Vd)/ F

Cp is target plasma concentration

22

Maintenance dose

(CpXCLxt)/F

23

Zero order elimination

Rate of elimination is constant and not based on the amount of drug in the body. Includes Phenytoin, ethanol, aspirin (at high doses)

24

First order elimination

Rate of elimination is directly proportional to the drug concentration. There is a constant fraction of drug eliminated per unit time.

This is flow-dependent elimination

25

Weak acids

Treat overdose with bicarbonate, because are ionized in basic environment.

Phenobarbital, methotrexate, aspirin

26

Weak bases

Trapped in acidic environments, treat overdose with ammonium chloride.

27

Weak bases

Trapped in acidic environments, treat overdose with ammonium chloride.

28

Phase 1 metabolism

Oxidation/reduction/hydrolysis (usually cyp450)

29

Phase 2 metabolism

Glucuronidation, acetylation, sulftation. Yields very polar, inactive metabolites that are renally excreted.

30

Phase 2 metabolism

Glucuronidation, acetylation, sulftation. Yields very polar, inactive metabolites that are renally excreted.

31

Efficacy of a drug

The maximal effect a drug can produce.

High efficacy drugs include analgesics, antibiotics, antihistamines, and decongestants.

32

Potency of a drug

The amount of drug needed for a given effect. Increased affinity for receptors.

Include chemotherapeutics, antihypertensives, and cholesterol drugs

33

Competitive antagonist effect on curve

Shifts to the right, decreases the potency. Flumazenil (on gaba)

34

Noncompetitive antagonist/irreversible competitive antagonist effect on curve

Shifts it down. Prevents maximal effect. (ketamine is noncompetitive, phenoxybenzamine is irreversible competitive on alpha receptors

35

Therapeutic index

A measurement of drug safety.

TD50/ED50 = median toxic dose/ median effective dose.

Safe drugs have high TIs.

Low TI drugs include theophylline, digoxin, lithium

36

Receptor and g protein class
A1
A2
B1
B2
M1
M2
M3
D1
D2
H1
H2
V1
V2

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