Pharm Basics

Question 1

Km

Answer 1

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

Question 2

Michaelis-Menten Equation

Answer 2

Vmax*S/Km+S

Question 3

Michaelis-Menten Equation

Answer 3

Vmax*S/Km+S

Question 4

Lineweaver Burk Plot

Answer 4

Plots against 1/V and 1/s

Question 5

X intercept on lineweaver burk?

Answer 5

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

Question 6

Y intercept on lineweaver burk

Answer 6

1/Vmax.

Question 7

Slope on lineweaver burk

Answer 7

Km/Vmax

Question 8

Slope on lineweaver burk

Answer 8

Km/Vmax

Question 9

Characteristics of a reversible competitive inhibitor

Answer 9

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

Decrease potency of an enzyme

Question 10

Characteristics of an irreversible competitive inhibitor

Answer 10

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

Decrease efficacy of an enzyme

Question 11

Characteristics of an irreversible competitive inhibitor

Answer 11

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

Decrease efficacy of an enzyme

Question 12

Noncompetitive inhibitor characteristics

Answer 12

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

Question 13

Bioavailability

Answer 13

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

Question 14

Volume of distribution equation

Answer 14

Amount of drug in the body/plasma drug concentration

Question 15

Drugs with low Vd

Answer 15

Remain mostly in blood, these include large/charged molecules

Question 16

Drugs with medium Vd

Answer 16

Mostly in EFC. Include small hydrophilic molecules

Question 17

Drugs with large Vd

Answer 17

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

Question 18

Half-life equation

Answer 18

(0.693 x Vd)/CL

Question 19

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

Answer 19

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

Question 20

Clearance equation

Answer 20

Rate of elimination of the drug/plasma drug concentration.

VdXke (elimination constant)

Question 21

Loading dose

Answer 21

(Cp X Vd)/ F

Cp is target plasma concentration

Question 22

Maintenance dose

Answer 22

(CpXCLxt)/F

Question 23

Zero order elimination

Answer 23

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

Question 24

First order elimination

Answer 24

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

Question 25

Weak acids

Answer 25

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

Question 26

Weak bases

Answer 26

Trapped in acidic environments, treat overdose with ammonium chloride.

Question 27

Weak bases

Answer 27

Trapped in acidic environments, treat overdose with ammonium chloride.

Question 28

Phase 1 metabolism

Answer 28

Oxidation/reduction/hydrolysis (usually cyp450)

Question 29

Phase 2 metabolism

Answer 29

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

Question 30

Phase 2 metabolism

Answer 30

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

Question 31

Efficacy of a drug

Answer 31

The maximal effect a drug can produce. High efficacy drugs include analgesics, antibiotics, antihistamines, and decongestants.

Question 32

Potency of a drug

Answer 32

The amount of drug needed for a given effect. Increased affinity for receptors. Include chemotherapeutics, antihypertensives, and cholesterol drugs

Question 33

Competitive antagonist effect on curve

Answer 33

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

Question 34

Noncompetitive antagonist/irreversible competitive antagonist effect on curve

Answer 34

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

Question 35

Therapeutic index

Answer 35

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

Question 36

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

Answer 36

``` q i s s q i q s i q s q s ```