Lehne: Pharmacology Adn1 Test 3-Chapter-4: Pharmacokinetics

Front 1

• Pharmacokinetics consists of four basic processes:

Back 1

absorption,
distribution,
metabolism, and
excretion

Front 2

• Pharmacokinetic processes determine the

Back 2

concentration of a drug at its sites of action and thereby determine the intensity and time course of responses

Front 3

• To move around the body, drugs must cross membranes by:

Back 3

(1) passing through pores,
(2) undergoing transport, or
(3) penetrating the membrane directly

Front 4

The most common method of crossing the membrane is:

Back 4

direct penetration of the membrane is the most common

Front 5

• P-glycoprotein is:

Back 5

found in the liver, kidney, placenta, intestine, and brain capillaries—
it can transport a variety of drugs out of cells.

Front 6

• For drugs to cross membranes:

Back 6

most drugs must dissolve directly into the lipid bilayer of the membrane.
Accordingly, lipid-soluble drugs can cross membranes easily,
whereas drugs that are polar or ionized cannot.

Front 7

• Acidic drugs ionize in:

Back 7

basic (alkaline) media,

Front 8

basic drugs ionize in:

Back 8

acidic media.

Front 9

• When there is a pH gradient between two sides of a membrane:

Back 9

o Acidic drugs will accumulate on the alkaline side.
o Basic drugs will accumulate on the acidic side

Front 10

• By manipulating urinary pH, we can employ ion trapping to:

Back 10

draw toxic substances from the blood into the urine, thereby accelerating their removal.

Front 11

• Absorption is defined as:

Back 11

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

Front 12

• Absorption is enhanced by:

Back 12

rapid drug dissolution,
high lipid solubility of the drug,
a large surface area for absorption, and
high blood flow at the site of administration.

Front 13

• Parenteral is used to mean:

Back 13

-by injection-.
The principal parenteral routes are intravenous,
subcutaneous, and
intramuscular

Front 14

• Intravenous administration has several advantages:

Back 14

rapid onset,
precise control over the amount of drug entering the blood,
suitability for use with large volumes of fluid, and
suitability for irritant drugs.

Front 15

• Intravenous administration has several disadvantages:

Back 15

high cost; difficulty;
inconvenience;
danger because of irreversibility; and
the potential for fluid overload,
infection, and embolism

Front 16

• Intramuscular administration has two advantages:

Back 16

suitability for insoluble drugs and
suitability for depot preparations

Front 17

• Intramuscular administration has two disadvantages:

Back 17

inconvenience and
the potential for discomfort

Front 18

• Subcutaneous administration has two advantages:

Back 18

suitability for insoluble drugs and
suitability for depot preparations

Front 19

Subcutaneous administration two disadvantages:

Back 19

inconvenience and
the potential for discomfort

Front 20

• Oral administration has the advantages of:

Back 20

ease,
convenience,
economy, and
safety

Front 21

• Oral preparations can differ in their properties despite having:

Back 21

the same drug dosage

Front 22

• Drug preparations are considered chemically equivalent if they:

Back 22

contain the same amount of the identical chemical compound (drug).

Front 23

• Preparations are considered equal in bioavailability if the drug they contain is: .

Back 23

absorbed at the same rate and to the same extent

Front 24

• The principal disadvantages of oral administration are:

Back 24

high variability and
possible inactivation by stomach acid, digestive enzymes, and
liver enzymes
(because oral drugs must pass through the liver before reaching the general circulation).

Front 25

• Induction of drug-metabolizing enzymes can have two therapeutic consequences:

Back 25

A drug can increase the rate of its own metabolism, thereby necessitating an increase in its dosage to maintain therapeutic effects.
Second, induction of drug-metabolizing enzymes can accelerate the metabolism of other drugs, necessitating an increase in their dosages.

Front 26

• Enteric-coated oral formulations are designed to:

Back 26

release their contents in the small intestine—not in the stomach.

Front 27

• Sustained-release oral formulations are designed to:

Back 27

release their contents slowly, thereby permitting a longer interval between doses

Front 28

• Distribution is defined as:

Back 28

the movement of drugs throughout the body

Front 29

• In most tissues, drugs can easily leave the vasculature through:

Back 29

spaces between the cells that compose the capillary wall

Front 30

• The term blood-brain barrier refers to:

Back 30

the presence of tight junctions between the cells that compose capillary walls in the central nervous system (CNS).
Because of this barrier, drugs must pass through the cells of the capillary wall (rather than between them) in order to reach the CNS.

Front 31

• The membranes of the placenta do not constitute:

Back 31

an absolute barrier to the passage of drugs. The same factors that determine drug movements across all other membranes determine the movement of drugs across the placenta.

Front 32

• Many drugs bind reversibly to:

Back 32

plasma albumin.
While bound to albumin, drug molecules cannot leave the vascular system.

Front 33

• If a patient is albumin deficient, it can cause:

Back 33

drug toxicities and resultant side effects because in highly protein-bound drugs, more drug will be available.

Front 34

• Drug metabolism (biotransformation) is defined as

Back 34

the enzymatic alteration of drug structure.

Front 35

• Most drug metabolism takes place in the liver and is catalyzed by:

Back 35

the cytochrome P450 system of enzymes.

Front 36

• The most important consequence of drug metabolism is:

Back 36

promotion of renal drug excretion (by converting lipid-soluble drugs into more polar forms).

Front 37

• Other consequences of drug metabolism are:

Back 37

conversion of drugs to less active (or inactive) forms,
conversion of drugs to more active forms, conversion of prodrugs to their active forms, and
conversion of drugs to more toxic or less toxic forms

Front 38

• Some drugs can induce (stimulate) synthesis of hepatic drug-metabolizing enzymes and can thereby

Back 38

accelerate their own metabolism and the metabolism of other drugs.

Front 39

• The term first-pass effect refers to:

Back 39

the rapid inactivation of some oral drugs as they pass through the liver after being absorbed

Front 40

• Most drugs are excreted by:

Back 40

the kidneys

Front 41

• Renal drug excretion has three steps:

Back 41

glomerular filtration,
passive tubular reabsorption, and
active tubular secretion.

Front 42

• Drugs that are highly lipid soluble undergo:

Back 42

extensive passive reabsorption back into the blood and therefore cannot be excreted by the kidney (until they are converted to more polar forms by the liver).

Front 43

• Bile is an important route of:

Back 43

excretion for certain drugs.

Front 44

• Drugs entering the intestine in bile may:

Back 44

undergo reabsorption back into the portal blood.
• This reabsorption, referred to as enterohepatic recirculation, can substantially prolong a drug’s sojourn in the body.

Front 45

• Drugs can be excreted into breast milk, thereby:

Back 45

posing a threat to the nursing infant.

Front 46

• For most drugs, there is a direct correlation between

Back 46

the level of drug in plasma and the intensity of therapeutic and toxic effects

Front 47

• The minimum effective concentration (MEC) is defined as:

Back 47

the plasma drug level below which therapeutic effects will not occur

Front 48

• The therapeutic range of a drug lies between:

Back 48

the MEC and the toxic concentration.

Front 49

• Drugs with a wide therapeutic range are:

Back 49

relatively easy to use safely,
whereas
drugs with a narrow therapeutic range are difficult to use safely.

Front 50

• The half-life of a drug is defined as:

Back 50

the time required for the amount of drug in the body to decline by 50%.

Front 51

• Drugs that have a short half-life must be administered:

Back 51

more frequently than drugs that have a long half-life

Front 52

• When drugs are administered repeatedly their levels will:

Back 52

gradually rise and then reach a steady plateau

Front 53

• The time required to reach plateau is equivalent to:

Back 53

about four half-lives.

Front 54

• The time required to reach plateau is independent of:

Back 54

dosage size,
although the height of the plateau will be higher with larger doses.

Front 55

• When plateau must be achieved quickly, a large initial dose is administered. This is called:

Back 55

a loading dose

Front 56

• A plateau is maintained by administering small doses. This is referred to as:

Back 56

a maintenance dose

Front 57

• The minimum effective concentration (MEC) is defined as:

Back 57

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

Front 58

• If plasma drug levels fluctuate too much between doses, the fluctuations could be reduced by:

Back 58

(1) giving smaller doses at shorter intervals (keeping the total daily dose the same),
(2) using a continuous infusion, or
(3) using a depot preparation.

Front 59

• For a drug with a long half-life, it may be necessary to use:

Back 59

a loading dose to achieve plateau quickly

Front 60

• When drug administration is discontinued, most (94%) of the drug in the body will be eliminated over:

Back 60

four half-lives.

Front 61

What is required for a drug to move through the body?
A) Selectivity and effectiveness
B) Ability to cross membranes
C) Development of an electric charge
D) A transporter protein

Back 61

B
In order to move through the body drugs must cross membranes. They cross membranes to enter the bloodstream, to exit the bloodstream and reach the site of action, and to undergo metabolism and excretion. Selectivity and effectiveness are not related to drug movement. Development of an electric charge (ionization) decreases a drug's ability to be absorbed. Transporter proteins are not required for drugs to move through the body.

Front 62

The nurse is preparing to give a medication for pain. The drug label states that it is "lipid soluble." What would be the nurse's expectation about how easily this drug could pass through a cell membrane?
A) Slowly
B) Rapidly
C) Unpredictably
D) Variably

Back 62

B
Cell membranes are composed of lipids; therefore, a lipid-soluble drug passes through quickly. A water-soluble drug passes through more slowly.

Front 63

Which is the most common way for drugs to cross cell membranes?
A) Direct penetration
B) Through channels and pores
C) Through transport systems
D) Bound to albumin

Back 63

A

Cell membranes are composed of lipids; therefore, a lipid-soluble drug passes through quickly. A water-soluble drug passes through more slowly.

Front 64

Which factor does NOT improve the rate of drug absorption?
A) Ability to dissolve readily
B) Large surface area
C) Rapid blood flow
D) Ionization

Back 64

D

When drugs become ionized they take on an electrical charge, which decreases their ability to cross membranes. The remaining processes improve absorption.

Front 65

What is the minimum amount of time over which an IV drug should be injected in order to minimize risk?
A) 10 seconds
B) 30 seconds
C) 60 seconds
D) 30 minutes

Back 65

C


IV drugs should be injected over at least 1 minute or more because all of the blood in the body is circulated about once every minute. This allows the drug to be diluted in the largest volume of blood possible.