Drug Actions: Pharmacodynamics and Pharmacokinetics

Question 1

definition of pharmacokinetics

Answer 1

movement of drug particles from GI-tract to body fluids

Question 2

3 processes of drug absorption

Answer 2

passive (high conc–>low);
active (requires a carrier to move drug across membrane);
pinocytosis- engulfs and carries drug across cell wall (water soluble drugs)

Question 3

metabolism 1st pass (liver)

Answer 3

1. drugs excreted after changed to water form
2. nothing happens to drug
3. drug metabolized into metabolite (equally or more active than original drug)

Question 4

Bioavailability

Answer 4

% of drug initially admin that reaches the systemic circulation so it can be used

Question 5

What is bioavailability affected by?

Answer 5

drug form
route of admin
GI mucosa and motility
food and other drugs
changes in liver metabolism caused by liver dysfunction or inadequate hepatic blood flow

Question 6

pharmacokinetics- distribution

Answer 6

process by which the drug becomes available to the body fluids and tissues

Question 7

3 factors that influence distribution

Answer 7

1. blood flow
2. protein binding
3. body tissue affinity

Question 8

protein binding

Answer 8

drug bind to varying degrees with proteins;

free-floating, unbound drugs are the ones with a pharmacologic effect

Question 9

protein binding %’s; high to low

Answer 9

over 89%- high pb drug
61-89%- mod/ high pb drug
under 30%- low pb drug

Question 10

Metabolism/ Biotransformation

Answer 10

liver is primary site;

in liver disease- not metabolizing drug well which leads to inc conc of drug and inc risk of toxicity

Question 11

Half-life (t1/2)

Answer 11

time it takes for one half of the drug conc to be eliminated from the body;
metabolism and elimination affect half life;
short half life- 4-8hrs
long- more than 24hrs

Question 12

Excretion/ Elimination

Answer 12

primary site- kidneys

urine pH affects excretion

Question 13

alkaline urine

Answer 13

excretion of weak acid drugs like ASA

Question 14

sodium bicarbonate

Answer 14

makes urine alkaline; used in ASA overdoses

Question 15

Pharmacodynamics

Answer 15

study of the way drugs affect the body;

drug concentration and its effect on the body

Question 16

pharmacodynamics: primary and secondary effect

Answer 16

primary- desirable

secondary- desirable or undesirable

Question 17

Dose response and maximum efficacy

Answer 17

relationship between the minimum amount vs the maximum amount of a drug needed to produce desired effects/response

Question 18

onset

Answer 18

time it takes to reach the minimum effective concentration

Question 19

Receptor Theory

Answer 19

drug binds to receptors on cell membrane;

bind to agonists or antagonists

Question 20

agonists

Answer 20

receptors that produce a response

Question 21

antagonists

Answer 21

receptors in which the drugs block response

Question 22

Nonspecific drug effect

Answer 22

drugs that affect various sites

Question 23

nonselective drug effect

Answer 23

drug works on various receptors

Question 24

4 categories of drug action

Answer 24

1. stimulation/depression
2. replacement (insulin, vitamins, minerals)
3. inhibition or killing organisms ( antiinfectives)
4. irritation (laxatives)

Question 25

Therapeutic Index

Answer 25

margin of safety of a drug

Question 26

low index vs high index

Answer 26

low index has narrow margin of safety;
high index has wide margin of safety
lethal dose/effective dose (closer to 1, greater the toxicity of drug)

Question 27

trough

Answer 27

rate of elimination of a drug

Question 28

Loading Dose (LD)

Answer 28

large initial dose when want an immediate drug response; normal doses follow

Question 29

Side Effects

Answer 29

physiologic effects not related to desired drug effects;

desirable or undesirable

Question 30

Adverse Reactions

Answer 30

more severe than side effects; unexpected, unintended effects of a drug;
always undesirable

Question 31

Drug interactions

Answer 31

a different action or effect of a drug as a result of an interaction with one or more other drugs (inside the body)

Question 32

Drug Incompatibility

Answer 32

a chemical or physical reaction that occurs between two or more drugs within a syringe, iv bag, or iv tubing (outside the body)

Question 33

Additive drug effect

Answer 33

sum of the effect of 2 drugs; can be desirable or undesirable
codeine and asa combined- greater pain relief (desirable)
bp med and narcotic- dec bp (undesirable)

Question 34

synergistic drug effect or potentiation

Answer 34

when 1 drug can potentiate the effect of another drug

Question 35

antagonistic drug effect

Answer 35

when 1 drug will antagonize effects of other drugs

antidotes (vit k and warfarin)

Question 36

drug-food interactions

Answer 36

can increase or decrease absorption;

dont combine tetracyclines and dairy