Chapter 4: Pharmacokinetics

Question 1

Pharmacokinetics

Answer 1

the study of drug movement throughout the body

Question 2

drugs usually pass through

Answer 2

cells
- because they are too large to pass through channels or pores

Question 3

most drugs lack

Answer 3

transport systems

Question 4

what is the general rule in chemistry

Answer 4

“like dissolves like”

Question 5

Cell membranes are composed primarily of lipids; therefore to directly penetrate membranes, a drug must be _________

Answer 5

lipid soluable (lipophilic)

Question 6

examples of polar molecules and ions

Answer 6

• quaternary ammonium compounds, pH dependent ionization, pH partitioning

Question 7

three ways to cross a cell membrane

Answer 7

• channels and pores
• transport systems (p glycoprotein)
• direct penetration

Question 8

p glycoprotein

Answer 8

transmembrane protein that transports a wide variety of drugs out of the cell

Question 9

liver

Answer 9

transports drugs into bile for elimination

Question 10

kideney

Answer 10

pumps drugs into the ursine for excretion

Question 11

placenta

Answer 11

transports drugs back into the maternal blood

Question 12

brain

Answer 12

pumps drugs into the blood to limit drugs access to the brain

Question 13

direct penetration of the membrane

Answer 13

• polar molecules dissolve in polar solvent
• most ions are unable to

Question 14

absorption

Answer 14

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

Question 15

rate of absorption determines

Answer 15

how soon the effects will begin

Question 16

amount of absorption help determine

Answer 16

how intense the effects will be

Question 17

5 factors affecting drug absorption

Answer 17

• rate of dissolution
• surface area
• bllod flow
• lipid solubility
• pH partitioning

Question 18

Intravenous (parenteral)
- barrier to absorption:
-absorption pattern:
- Advantages:
- disadvantages

Answer 18

• barrier to absorption: none
  -absorption pattern: instant and complete
• Advantages: quick, large volume, control, irritants
• disadvantages: cost, fluid overload, error

Question 19

intramuscular
- barrier to absorption:
-absorption pattern:
- Advantages:
- disadvantages

Answer 19

• barrier to absorption: nothing significant
  -absorption pattern: variable (solubility/blood flow)
• Advantages: depot, good fro poorly soluble drugs
• disadvantages: discomfort, inconvenience

Question 20

Oral (enteral)
- barrier to absorption:
-absorption pattern:
- Advantages:
- disadvantages

Answer 20

• barrier to absorption: stomach or intestine epithelial cells and capillary walls
  -absorption pattern: highly variable (drug solubility and stability, food, other drugs, GI, pH, gastric emptying, coatings, ect.)
• Advantages: easy, convient, safe
• disadvantages: variability, inactivation, swallowing (client, local irritation

Question 21

Subcutaneous
- barrier to absorption:
-absorption pattern:

Answer 21

• barrier to absorption: no significant
  -absorption pattern: similar to IM administration

Question 22

distribution

Answer 22

movement of drugs through the body

Question 23

drug distribution is determined by which three factors

Answer 23

• blood flow to tissues
• exiting the vascular system
• entering cells

Question 24

blood flow determines

Answer 24

the rate of delivery

Question 25

how do abscesses and effect blood flow

Answer 25

- soild tumors have limited blood supply

Question 26

Blood Brain barrier

Answer 26

thight junctions between the cells that comprise the walls of most capillaries in the central nervous system

Question 27

only drugs that are __________ or that habe a ________ can cross the blood brain barrier to a significant degree

Answer 27

lipid soluble transport system

Question 28

risk with placental drug transfer

Answer 28

brith defects: gross malformations, low birth rate, drug dependent baby, ect.

Question 29

what is the most abundant and important plasma protein

Answer 29

albumin

Question 30

albumin levels in the body influence

Answer 30

drug distribution

Question 31

albumin

Answer 31

- large molecule that always remains in the bloodstream - affects drug distribution - " protein binding" important factor in pharmacokinetics

Question 32

drug metabolism is also known as

Answer 32

biotransformation

Question 33

drug metabolism

Answer 33

defined as the chemical alteration of drug structure

Question 34

drug metabolism most often takes place in the

Answer 34

liver (Cytochrome P450 system)

Question 35

5 therapeutic consequences of drug metabolism

Answer 35

- accelerated renal drug excretion - drug inactivation - increased therapeutic action - activation of prodrugs - increased or decreased toxicity

Question 36

5 special considerations in drug metabolism

Answer 36

- age - induction of CYP450 system - " first pass" effect - nutritional status (reduced cofactors) - competition amoungst drugs

Question 37

first pass effect

Question 38

excretion

Answer 38

removal of drugs from the body

Question 39

factors that modify renal drug excretion

Answer 39

- ph dependent ionization - competition for tubular active transport - age

Question 40

non renal routes o f drug excretion

Answer 40

- breast milk - bile (enterohepatic recirculation) - lungs (anaesthesia) - sweat and saliva

Question 41

what are the 4 time courses of drug responses

Answer 41

- plasma drug levels - single dose time course - drug half life - drug levels produced with repeated doses

Question 42

half life

Answer 42

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

Question 43

half life determines

Answer 43

dosing interval ( how often you take the drug)

Question 44

steady state (plateau) level

Answer 44

4-5 half lives