2. Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Question 1

process of drug movement through the body that is necessary to achieve drug action

Answer 1

pharmacokinetics

Question 2

4 processes of pharmacokinetics

Answer 2

• absorption
• distribution
• metabolism
• excretion

Question 3

movement of the drug into the bloodstream

Answer 3

absorption

Question 4

purpose of enteric coated drugs (EC)

Answer 4

resist disintegration in the gastric contents of the stomach (wait until small intestine)

Question 5

T/F: enteric coated (EC) drugs and extended release (ER) drugs should not be crushed

Answer 5

True

Question 6

Which route is going to be absorbed the quickest?

Answer 6

IV (already in the bloodstream); IM and subcutaneous will both be quicker than oral (enteral)

Question 7

Which version of transport will be absorbed quicker: active or passive?

Answer 7

Passive; does not require molecules or energy -> can diffuse across membranes

Question 8

What types of molecules cannot diffuse across membranes (passive)?

Answer 8

water-soluble and ionized (positively or negatively charged)

Question 9

What types of molecules can diffuse passively across membranes?

Answer 9

lipid-soluble and nonionized

Question 10

oral drugs pass from intestinal lumen to the liver via the portal vein and undergo metabolism -> reduces amount of active drug

Answer 10

first pass effect

Question 11

percentage of administered drug available for activity

Answer 11

bioavailability

Question 12

Factors that alter bioavailability

Answer 12

• drug form
• route of administration
• gastric mucosa and motility
• administration w/ food and other drugs
• changes in liver metabolism (liver dysfunction)

Question 13

movement of drug from circulation to the body tissues

Answer 13

distribution

Question 14

What occurs w/ drugs that are highly protein-bound?

Answer 14

less active drug available -> drug bound to protein is inactive

Question 15

What is the effect of taking at least 2 meds that are both highly protein-bound?

Answer 15

both drugs will compete for protein binding -> higher free active drug -> may need smaller dose

Question 16

What types of drugs are able to cross the blood brain barrier (BBB)

Answer 16

highly lipid soluble and of low molecular weight can cross by diffusion while other may cross via transport proteins

Question 17

What is considered before giving drugs during pregnancy?

Answer 17

risk-to-benefit ratio

Question 18

process by which the body chemically changes drugs into a form that can be excreted; aka biotransformation

Answer 18

metabolism

Question 19

liver enzymes that covert drugs into metabolites

Answer 19

cytochrome P450 enzymes

Question 20

time it takes for the amount of drug in the body to be reduced by half

Answer 20

half life

Question 21

occurs when the amount of drug being administered is the same amount of the drug being eliminated

Answer 21

steady state (plateau drug level)

Question 22

What is a loading dose?

Answer 22

a large initial dose of a drug w/ a long half life -> allows therapeutic effects to take place while reaching a steady state

Question 23

elimination of drugs from the body

Answer 23

excretion

Question 24

main route of drug excretion

Answer 24

kidneys

Question 25

What must you be aware of when administering drugs?

Answer 25

renal lab values (will the drugs be excreted properly)

Question 26

study of effects of drugs on the body

Answer 26

pharmacodynamics

Question 27

amount of drug needed to elicit a specific physiologic response

Answer 27

potency

Question 28

high vs low potency

Answer 28

- high: produces significant therapeutic response w/ low concentration - low: produces minimal therapeutic response at low concentrations

Question 29

point at which increasing a drug's dosage no longer increases desired therapeutic response

Answer 29

maximal efficacy

Question 30

describes relationship between therapeutic dose of a drug (ED50) and the toxic dose of a drug (TD50); difference between the 2 points

Answer 30

therapeutic index (TI)

Question 31

dose of drug that produces a therapeutic response in 50% of the population

Answer 31

ED50

Question 32

dose of a drug that produces a toxic response in 50% of the population

Answer 32

TD50

Question 33

What does it mean if a drug has a narrow (low) therapeutic index?

Answer 33

the therapeutic dose and toxic doses are close together -> require close monitoring for pt safety

Question 34

highest plasma concentration of a drug at a specific time; indicates rate of absorption; usually 30-60 minutes by IV

Answer 34

peak drug level

Question 35

lowest plasma drug concentration; drug level drawn right before next dose without regard to administration

Answer 35

trough drug level

Question 36

What determines the activity of most drugs?

Answer 36

ability of the drug to bind to a specific receptor; more active the better the drug fits at the receptor site

Question 37

drugs that activate receptors and produce a desired response

Answer 37

agonists

Question 38

drugs that prevent receptor activation and blocks a response

Answer 38

antagonists

Question 39

T/F: antagonists only decrease cellular action

Answer 39

False; may increase or decrease cellular action depending on the action of the chemical messenger that is blocked

Question 40

drugs that affect multiple receptor sites

Answer 40

non-specific drugs

Question 41

drugs that affect multiple receptors types

Answer 41

non-selective drugs

Question 42

7 mechanism of drug actions

Answer 42

- stimulation - depression - irritation - replacement - cytotoxic action - antimicrobial action - modification of immune status

Question 43

unintentional, unexpected reactions to drug therapy that occur at normal dosage; may be mild to life-threatening

Answer 43

adverse drug reactions (ADRs)

Question 44

secondary effects to drug therapy

Answer 44

side effects

Question 45

T/F: all drugs have side effects

Answer 45

True

Question 46

Most common side effects found in drugs?

Answer 46

N/V/D

Question 47

occurs when drug levels exceed a therapeutic range; may be due to overdose or drug accumulation

Answer 47

drug toxicity

Question 48

refers to study of genetic factors that influence an individual's response to a specific drug

Answer 48

pharmacogenetics

Question 49

decreased responsiveness to a drug over the course of therapy; individual will require higher dosage of drug to achieve same therapeutic response

Answer 49

Drug tolerance

Question 50

acute, rapid decrease in response to a drug; may occur after first dose or several doses

Answer 50

tachyphylaxis

Question 51

drug response not attributed to the chemical properties of the drug; can be positive or negative; psychological origin but physiologic response

Answer 51

placebo effect

Question 52

changes that occur in the absorption, distribution, metabolism, and excretion of one or more drugs (ex. taking enzyme inducers and enzyme inhibitors together)

Answer 52

pharmacokinetic interactions

Question 53

interactions that result in additive, synergistic, or antagonistic drug effects

Answer 53

pharmacodynamic interactions

Question 54

when 2 drugs are administered together and the response is equal to the effects of the 2 drugs together (2+2=4)

Answer 54

additive effect

Question 55

when 2 drugs are given together, the clinical effects of the 2 drugs is greater than their separate effects (2+2>4)

Answer 55

synergistic effect

Question 56

when 2 drugs are administered together and one drug reduces or blocks the effects of the other (2+2<4)

Answer 56

antagonistic effect

Question 57

Name 4 things drugs can interact with?

Answer 57

- other drugs - nutrients: foods increase/decrease or delay body's response to drugs (grapefruit and CYP450 enzyme) - labs: cephalosporin can alter urine glucose/ketone tests - photosensitivity: skin reaction from sunlight (usually UVA); causes photosensitive and photoallergic reactions

Question 58

List 4 receptor families

Answer 58

- cell membrane-embedded enzymes - ligand-gated ion channels - G protein-coupled receptors - transcription factors

Question 59

drug binds to domain on cell surface -> activates enzyme inside cell which causes response (fast acting)

Answer 59

cell membrane-embedded enzymes

Question 60

channel crosses the cell membrane -> when it opens, ions flow in and out -> mainly affects Na and Ca (fast acting)

Answer 60

ligand-gated ion channels

Question 61

drug activates receptor -> receptor activates G protein -> binds w/ GTP -> activates the effect (fast acting)

Answer 61

G protein-coupled receptors

Question 62

found in the cell nucleus on DNA -> activation regulates protein synthesis (prolonged)

Answer 62

transcription factors

Question 63

drugs that increase drug metabolism -> promote drug elimination and decrease plasma concentration (decreased action)

Answer 63

enzyme inducers

Question 64

drugs that decrease drug metabolism -> increase plasma concentration and potential toxicity

Answer 64

enzyme inhibitors