Pharmacology

Question 1

bioavailability

Answer 1

proportion of administered drug that reaches the systemic circulation

Question 2

pharmacokinetics

Answer 2

what the body does to the drug

Question 3

pharmcodynamics

Answer 3

what the drug does to the boyd

Question 4

to measure bioavailability

Answer 4

% of proportion measured relative to IV dose

Question 5

IV administration mean

Answer 5

drug is 100% bioavailable

Question 6

on a graph of bioavailability the area under it

Answer 6

is an indicator of total body exposure to the drug

Question 7

factors which influence bioavailability

Answer 7

• nature of the drug (chemical, peptide)
• GI transit and digestion
• first pass metabolism
• route of admin
• lipophilicity

Question 8

Bioavailability and GI transit and digestion

Answer 8

Patients with vomiting and diarrhoea have faster transit through GI tract- therefore tablets many not be totally absented.

Question 9

patients who are sick

Answer 9

may not absorb any of the drug

Question 10

drugs can be broken don by

Answer 10

enzymes in the GI tract

Question 11

what is first pass metabolism

Answer 11

breakdown of drug by liver before it reaches systemic circulation
-blood flow from GI tract passes through liver via hepatic portal vein

Question 12

route of admin e.g

Answer 12

• IV

- orally

Question 13

IV

Answer 13

straight into the bloodstream

Question 14

Oral

Answer 14

easy and well tolerated

Question 15

IM

Answer 15

via capillaries/lympathic system- slower absorption

Question 16

respiratory

Answer 16

across plasma membrane- rapid absorptions

Question 17

administrations which involve

Answer 17

the drug accessing a blood supply quickly are the quickest

Question 18

why is oral administration not perfect

Answer 18

due to first pass metabolism decreasing bioavailability

Question 19

lipohilicity

Answer 19

the more lipophilic/hydrophobic molecules are the more that can pass through the phospholipid bilayer of cells, increasing conc of drug in tissues

Question 20

many drugs are

Answer 20

weak acids

Question 21

many drugs are weak acts so

Answer 21

are in equilibrium between ionised and unionised form

e.g.Uncharged + lipophilic or charged and lipophobic

Question 22

the lower the pKa the

Answer 22

stronger the acid

Question 23

pKa

Answer 23

pH at which [ionised]= [unionised

Question 24

pl

Answer 24

isoelectric point

Question 25

pl is

Answer 25

the pH at which there is no net charge

Question 26

volume of distribution

Answer 26

represent the volume in which total amount of drug would need to be dissolved to match plasma concentration

Question 27

the higher th vd

Answer 27

the lower drug vol in the plasma= more in tissue

Question 28

after absorption

Answer 28

drug equilibrate between plasma and tissues e.g. adipose tissue

Question 29

calculating Vd

Answer 29

amount of drug in the body (dose) (mg)/ plasma concentration (mg/mL)

Question 30

factors affecting Vd

Answer 30

- drug size - lipophilicity - lasma protein binding - body composition - patients, age, gender - diff body fat composition

Question 31

Vd and plasma protein bidning

Answer 31

if drug bound to proteins in plasma, its generally not going to enter the tissue as proteins done bass into tissues

Question 32

Vd and body composition

Answer 32

e. g. inhale anaestheics- very fat soluble- drug absorbed into fatty tissue the back into body, very diff to control level of anaesthesia - why obese people are asked to lose weight before surgery

Question 33

how is Vd measured

Answer 33

measured experimentally following iv administration of known amount of drug

Question 34

high plasma [drug] =

Answer 34

ow Vd= drug not widely distributed, restricted to plasma compartment

Question 35

low plasma [drug]=

Answer 35

high Vd= drug widely distributed in other tissues

Question 36

clearance is

Answer 36

the volume of plasma cleared of the active compound per unit time

Question 37

hepatic clearance

Answer 37

by liver- metabolism

Question 38

renal clearance

Answer 38

by kidney- excretion -predominant route

Question 39

zero order

Answer 39

linear e.g. alcohol | -

Question 40

first order

Answer 40

exponential- most drugs | -constant proportion of drug cleared per unit time

Question 41

clearance can not be increased regardless of how much more drug you add if

Answer 41

all enzymes are saturated

Question 42

clearance=

Answer 42

[drug in urine] x urine flow rate/ [drug in plasma]

Question 43

clearance units

Answer 43

mL/min

Question 44

factors affecting renal clearance

Answer 44

- kindey function - lipophilicity - plasma protein binding

Question 45

plasma half life

Answer 45

-time taken for plasma conc of a drug to reduce by half

Question 46

drug targeting

Answer 46

targeting of drug delivery to site of action

Question 47

why is drug targeting important

Answer 47

- reduces side effects - allows a lower does to be given - more predictable side effects

Question 48

drug targeting exploits

Answer 48

property of target tissue

Question 49

sometime high bioavailability isn't desirable

Answer 49

systemic effect not desirable or necessary

Question 50

direct application: suppositiories/enemas

Answer 50

anti-inflammatory drugs

Question 51

oral drugs

Answer 51

- enteric coated- delayed release 9time/ pH release) | - prodrugs converted by gut bacteria

Question 52

sulfalazine

Answer 52

uses prodrug converted by gut bacteria

Question 53

targeted inflamed tissue

Answer 53

monoclonal antibodies against cytokines

Question 54

prodrugs are good because

Answer 54

they will prevent damage to the stomach