Introduction to Pharmacokinetics

Question 1

4 stages of drugs

Answer 1

ADME
absorption
distribution
metabolism
elimination

Question 2

absorption–3 times

Answer 2

dissolution
absorption
circulation

Question 3

2 types of passive absorption

Answer 3

filtration
diffusion
dont require energy and cant proceed against gradients

Question 4

passive filtration determined by?

Answer 4

osmotic/hydrostatic pressure differential

Question 5

passive diffusion determined by?

Answer 5

concentration gradient

most commonly utilized by drugs

Question 6

passive absorption also depends on?

Answer 6

ionization status

Question 7

2 ionization forms of drugs in body

Answer 7

ionized and unionized

must add up 100%

Question 8

ionized compound solubility

Answer 8

lower lipid solubility; higher water solubility

do not easily diffuse across lipid bilayer membranes

Question 9

unionized compounds solubility

Answer 9

higher lipid solubility; lower water solubility

easily diffuse across lipid bilayer membranes

Question 10

ionization status depends on 2 factors

Answer 10

pka of medication (propensity of a compound to donate protons)
pH of membrane gradient/milieu

Question 11

2 important areas of body where pH varies and commonly impacts ionization status

Answer 11

GI tract

kidneys

Question 12

when is there a 50/50 ratio of ionized to unionized?

Answer 12

when pka=ph

Question 13

base drugs become more unionized when?

Answer 13

as ph goes up

Question 14

acid drugs become more unionized whe?

Answer 14

when ph goes down

Question 15

what happens to ionized drugs?

Answer 15

are eliminated

do not get absorbed in GI tract or reabsorbed in kidney

Question 16

what happens to unionized drugs?

Answer 16

are NOT eliminated

readily get absorbed in GI tract or reabsorbed in kidney

Question 17

active absorption/transport is associated with?

Answer 17

energy requiring
saturable (competitive inhibition by other drugs)
movement against gradients

Question 18

facilitated diffusion is different from active transport how?

Answer 18

does NOT require energy

does NOT proceed against gradients

Question 19

2 stages for drugs related to serum protein binding

Answer 19

bound

unbound (active)

Question 20

alpha represents what?

Answer 20

unbound fraction
small alpha=smaller unbound
alpha is opposite of % protein bound

Question 21

What happens when there is low protein binding with low displacement? (30% bound; 70% free–>10% competition)

Answer 21

3% absolute change yet 4.3 % relative change

Question 22

high protein binding with low displacement–what happens (98% bound; 2% free–>10% competition)

Answer 22

10% absolute change yet 500% relative change

Question 23

what does metabolism do?

Answer 23

increases likelihood of drug elimination from body

alteration of drug to 1 or more chemically diff compounds (metabolites) which are pharmacologically active or inactive

Question 24

Are metabolites more or less active than the parent compound?

Answer 24

can be either more or less active

Question 25

2 main types of biotransformation reactions used by body

Answer 25

phase 1 and phase 2

Question 26

What are phase 1 reactions?

Answer 26

formation of new or modified functional group or cleavage (oxidation, reduction, hydrolysis)
CYP 450

Question 27

Phase 2 reaction

Answer 27

conjugation (covalent linkages–glucuronidation, sulfation, acetylation) with an endogenous substance (glucuronic acid, sulfate, glycine)

Question 28

CYP450 naming

Answer 28

family–numbers
subfamily–capital letter
individual–numbers
ex: 2C19

Question 29

CYP 450 main sites of actin

Answer 29

liver
GI tract
brain
kidney

Question 30

CYP 450 different drug types

Answer 30

substrate needs CYP 450 to be metabolized
inducers–induces CYP 450 system
inhibitors–inhibits CYP 450 system

Question 31

first pass metabolism/effect what is it?

Answer 31

orally administered drugs that go straight to liver (gets chewed up to be inactive)

Question 32

routes of elimination

Answer 32

liver and kidneys are primary
lungs
skin
bile/feces

Question 33

elimination of parent drug vs metabolite

Answer 33

active vs inactive

ionization status

Question 34

elimination–what can necissitate a dosing change?

Answer 34

reduced renal or hepatic function

Question 35

3 main processes of renal elimination

Answer 35

passive glomerular filtration (blood flow dependent)
passive tubular diffusion (passive or distal tubules–ionization and conc status dependent)
active tubular secretion (weak acids/bases secred into proximal tubules