Chapter 4

Question 1

what are the 4 phases of pharmacokinetics?

Answer 1

Absoprtion
Distribution
Metabolism
Excretion

Question 2

What are the 3 ways that drugs cross a cell membrane?

Answer 2

1. Passage through channels or pores
2. passage with the aid of a transport system
3. Direct penetration of the membrane itself.

Question 3

In order for a drug to have effect, it needs to ___

Answer 3

enter a cell

Question 4

In order for a drug to cross a cell membrane, what property do they need to posess?

Answer 4

Lipophilic

- lipid soluble

Question 5

elimination: ___ + ___

Answer 5

metabolism + excretion

Question 6

the most importan transporter protein that takes drugs out cells is:

Answer 6

P Glycoprotein

Question 7

Define: Absorption

Answer 7

the movement of a drug from its site of administration into the blood.

Question 8

the ___ of absorption determines how ___ effects will begin.

Answer 8

rate, soon

Question 9

the rate of dissolution helps to determine the rate of ___

Answer 9

absorption

Question 10

Absorption depends on these: (5)

Answer 10

1. Rate of dissolution- dissolving in stomach/intestines
2. Surface area- larger surface area: ^ absorption
3. Blood flow- ^ then absorption is fast
4. Lipid solubility- ^ absorbed faster, low absorbed slow
5. pH partitioning- basic is attracted to acidic

Question 11

the routes of administration that are the most commonly used are:

Answer 11

1. enteral (GI tract)

2. Parentaral ( Outside the GI tract- injection)

Question 12

The principle paranteral routes of med administration are:

Answer 12

1. intravenous
2. subcutaneous
3. intramuscular

Question 13

the route by which a medication is administered will significantly effect both the ___ and the ___ of effects

Answer 13

onset, intensity

Question 14

IV medication administration:

Answer 14

• no barriers to absorption: straight into blood
• Complete and instantaneous ( no first pass effect)
• Advantages: rapid onset, control of dose, ^ fluid volume dose, can use irritant drugs bc its diluted
• Disadvantages: ^ cost, difficult, inconvenient, IRREVERSIBLE ONCE GIVEN, infection, embolism

Question 15

You should take at least ____ to administer IV drugs

Answer 15

1:00 minute

Question 16

How can IV insertion create an embolism?

Answer 16

• damage to the venous wall, creating thrombus
• Injection of hyper and hypotonic solutions can destroy RBC’s. debri from these cells can make embolism
• powder drug not shaken enough

Question 17

IM medication administration:

Answer 17

• barrier: capillary wall
• absorption: depends on water solubility & blood flow

Advantages: can be used for admin of poorly soluble drugs, depot preparations (depo privara birth control shot)

Disadvantages: Hurts, inconvenient, local tissue injury, possible nerve damage, bleeding risk for those on anticoagulants

Question 18

Subcut medication administration:

Answer 18

• barrier: pass through spaces between cells of the capillary wall

Advantages: same as IM
disadvantages: same as IM

Question 19

Oral medication administration:

Answer 19

• barriers: layer of epithelial cells, capillary wall
• Absorption: highly variable due to many factors…

Advantages: easy, convenient, inexpensive, safer
Disadvantages: variability, inactivation, local irritation, patient responsibility

Question 20

Factors that influence absorption of Oral medications: (6)

Answer 20

1. solubility and stability of the drug
2. gastric and intestinal pH
3. gastric emptying time
4. food in the gut
5. coadministration of other drugs
6. special coating on the drug

Question 21

Enteric coasted oral preparations protect what? (2)

Answer 21

1. drug from acid and pepsin in stomach

2. stomach from drug that cause cause gastric discomfort

Question 22

defined as drug movement from the blood to the interstitial space of tissues and from there into the cells

Answer 22

distribution

Question 23

Distribution is determined by 3 major factors:

Answer 23

1. blood flow to tissues- except abcess & tumors
2. the ability of a drug to exit the vascular system
3. the ability of drugs to enter the cell

Question 24

drugs that are bound to albumin have an extended:

Answer 24

half-life and distribution phase

Question 25

Drug metabolism is also known as ___ and is defined as__

Answer 25

biotransformation,

the chemical alteration of drug structure

Question 26

what performs the metabolism of drugs in the liver?

Answer 26

Hepatic Drug- Metabolizing Enzymes: Cytochrome P450 system (CYP)

Question 27

the most important consequences of drug metabolism is:

Answer 27

promotion of renal drug excretion

Question 28

in infants, drug metabolism capacity is limited, why?

Answer 28

bc their liver doesn’t develop fully until their 1 yr old.

Question 29

The first-pass effect refers to:

Answer 29

the rapid hepatic inactivation of certain oral drugs.

Question 30

If the capacity of the liver to metabolize a drug extremely high, that drug can be ___

Answer 30

completely inactivated on its first pass through the liver.

“First Pass Effect”

Question 31

if renal failure occurs, both the ___ and ___ of drug responses may occur.

Answer 31

duration and intensity

Question 32

Urinary excretion of drugs occurs from 3 processes in kidney:

Answer 32

1. glomeruluar filtration
2. passive tubular reabsorption
3. active tubular secretion

Question 33

Non renal excretion of drugs:

Answer 33

breast milk (only lipid soluble drugs can exit)
Bile- pooped out or reabsorbed through portal blood
Lungs- volatile anesthetics
Small amounts in sweat and saliva

Question 34

For most drugs, there is a direct correlation between ___ and __ responses and the ___ of drug present in the plasma

Answer 34

therapeutic and toxic responses and the amount of drugs present in the plasma

Question 35

Minimum Effective Concentration (MEC)

Answer 35

the plasma drug level below which therapetuci effects will not occur.

Question 36

the plasma level which toxic effects begin

Answer 36

toxic concentration

Question 37

range of plasma drug levels that fall between the MEC and toxic concentration:

Answer 37

therapeutic range

Question 38

the objective of drug dosing:

Answer 38

maintain plasma drug levels within the therapeutic range

Question 39

Drug Hal-Life

Answer 39

time required fro the amount of drug in the body to decrease by 50%

Question 40

the drug ___ determines the dosing interval

Answer 40

half life

Question 41

when the amoutn of drug eliminated between doses equals the ______, average drug levels will remain constant and plateau

Answer 41

doses administered

Question 42

if doses remain constant, plateau will be reached in ____

Answer 42

4 half-lives

Question 43

What are 3 techniques to reduce fluctuations in drug levels?

Answer 43

1. administer drugs by continuous infusion
2. administer a depot preparation
3. reduce both the size and dosing interval of each dose