Pharmacokinetics

Front 1

4 components of pharmacokinetics?

Back 1

1) Administration
2) Absorption
3) Distribution
4) Elimination

Front 2

During the drug reaction when does the process shift from pharmacokinetics to pharmacodynamcis?

Back 2

When the drug reaches the site of action (See slide 3 of notes).

Front 3

1st-pass effect?

Back 3

This is when much of the drug concentration is lost primarily due to the liver or gut wall.
After the drug is swallowed digestive enzymes break it down and deliver it to the hepatic portal system.

Front 4

Primary method of avoiding 1st-pass effect?

Back 4

Parenteral administration

Front 5

An enteral method of administration to avoid 1st-pass?

Back 5

sublingual

Front 6

Limitations of sublingual admin?

Back 6

1) Only limited amount can be admin.
2) Some drugs can't be absorbed by oral mucosa.

Front 7

When would one chose to admin a rectal suppository?

Back 7

1) Necessary if the pt is vomiting or unconscious
2) To treat a local condition

Front 8

Cons of suppositories?

Back 8

1) Can irritate rectal mucosa
2) Some drugs can't be absorbed through the rectal mucosa

Front 9

Major benefit of inhalation admin?

Back 9

1) Large surface area for absorption

Front 10

Major issue with inhalation admin?

Back 10

Difficult to predict how much drug will reach the target tissue

Front 11

2 issues with injections?

Back 11

1) Risk of infection
2) Difficult to self-admin

Front 12

4 types of injections?

Back 12

1) Intravenous
2) Intra-arterial
3) Intramuscular
4) Subcutaneous

Front 13

What type of IV injection increases the risk of adverse reactions?

Back 13

Bolus injection

Front 14

Why is intra-arterial injection dangerous?

Back 14

b/c of the high pressure in the arterial system.

Front 15

Why is subcutaneous injection used over the others?

Back 15

1) Local response
2) Slower absorption

Front 16

When is intramuscular injection recommended?

Back 16

1) Local treatment
2) Prolonged release

Front 17

Issue with topical admin?

Back 17

Often poorly absorbed through the skin.

Front 18

Condition for transdermal admin to work correctly?

Back 18

Must penetrate skin and not degrade in the dermis.

Front 19

Absorption of a drug depends on what two factors?

Back 19

1) Blood flow
2) Drug concentration

Front 20

Bioavailability

Back 20

Extent to which the drug reaches systemic circulation.

Front 21

Bioavailability depends on what two factors?

Back 21

1) The ability of the drug to cross the plasma membrane.
2) Route of admin.

Front 22

What 4 factors influence how a drug will diffuse?

Back 22

1) Ionization's effect
2) Diffusion trapping
3) Diffusion between tight junctions
4) Osmosis

Front 23

Explain diffusion trapping?

Back 23

A drug that is to be excreted depends on the pH of the urine. If the pH of the urine is altered the drug can be kept or trapped in the body.

Front 24

4 types of absorption?

Back 24

1) Passive diffusion
2) Facilitated diffusion
3) Active transport
4) Endocytosis

Front 25

Distribution

Back 25

Movement of drug to target site.

Front 26

4 factors that influence distribution?

Back 26

1) Membrane/tissue permeability
2) Blood flow
3) Binding to plasma proteins
4) Binding to subcellular compartments

Front 27

Define volume of distribution

Back 27

The amount of drug administered divided by the concentration of drug in plasma.

Front 28

Why is volume of distribution used?

Back 28

It's the easiest way to determine where the drug will go through the body.

Front 29

If the Vd is less then the body fluid volume?

Back 29

We can assume that the drug will be retained in the blood

Front 30

If the Vd is greater than the body fluid volume?

Back 30

We can assume that the drug will be sequestered in the tissue.

Front 31

3 popular sites for drug storage?

Back 31

1) Fat
2) Bone
3) Muscle

Front 32

2 possible adverse consequences of drug storage?

Back 32

1) Toxicity -> local damage
2) Reservoir effects

Front 33

Two possible consequence from the reservoir effect?

Back 33

1) Drug doesn't reach the target tissue
2) Drug slowly leaks from the reservoir eventually reaching the target tissue, just much later than expected

Front 34

Describe biotransformation.

Back 34

The drug is metabolized (primarily in the liver). Biotransformation is responsible for the 1st-pass effect.

Front 35

4 types of biotransformation reactions

Back 35

1) Oxidation
2) Reduction
3) Hydrolysis
4) Conjugation

Front 36

For a biotransformation reaction to occur what must be present?

Back 36

An enzyme.

Front 37

2 possible processes of enzyme induction?

Back 37

1) Storage of enzymes (or overall production of more)
2) The body breaks down less enzymes -> enzyme sticks around in body longer

Front 38

Function of elimination that determines tolerance?

Back 38

Enzyme induction

Front 39

Excretion

Back 39

Removal of the drug from the body (primarily occurs in the kidneys)

Front 40

What process helps aid excretion?

Back 40

Biotransformation

Front 41

Oxidation

Back 41

Adding of Oxygen mol. and removing the Hydrogen mol.

Front 42

Reduction

Back 42

Removing of a Hydrogen mol. and adding an Oxygen mol.

Front 43

Hydrolysis

Back 43

Breaking down of the drug into two parts.

Front 44

Conjugation

Back 44

Taking the intact drug or a product of: oxidation, redox or hydolysis reaction and coupling it with something else of the body

Front 45

Clearance

Back 45

Process by which the active form of the drug is removed from the body

Front 46

Formula for systemic clearance?

Back 46

Rate of drug elimination/plasma drug concentration.

Front 47

Formula for organ clearance?

Back 47

Q*(Ci-Co)/ci

Q: Blood flow to organ
Ci: concentration of incoming drug
Co: concentration of outgoing drug

Front 48

Half-life

Back 48

Amount of time necessary to reduce the remaining drug concentration to 50%.

Front 49

Half-life depends on what two factors?

Back 49

1) Clearance (CL)
2) Volume of distribution (Vd)

Front 50

What happens if a pt doesn't have normal rate of elimination?

Back 50

leads to an increased risk of toxicity->adverse effects.

Front 51

Why are dosing schedules important to a PT?

Back 51

Dosing schedules help determine the pt's ability to perform PT.

Front 52

list of factors affecting elimination?

Back 52

1) Genetics
2) Disease
3) Age
4) Gender
5) Drug interactions
6) Diet
7) impaired GI motility (i.e. SCI pt)
8) Other (i.e., environmental factors)