Drug Movement

Question 1

What are the X4 Elements of Pharmacokinetics? (ADME)

Answer 1

• How body responds to drug (kinetics-moves)
  1) Absorption
  2) Distribution
  3) Metabolism
  4) Excretion/Elimination

Question 2

What is Absorption?

Answer 2

Absorption from site of distribution (once left bloodstream,)

Question 3

What is Distribution?

Answer 3

How the drug reversibly leaves the bloodstream and is dispersed into extracellular and intracellular compartments. (via plasma)

Question 4

What is Metabolism?

Answer 4

Drug transformation by organs

Question 5

What is Excretion?

Answer 5

How drug exits the body

Question 6

What are X2 mechanisms how a drug moves around the body?

Answer 6

• Bulk flow- (via bloodstream)

- Diffusion

Question 7

What is Passive Diffusion?

Answer 7

• Directly through lipids/aqueous pores in the membrane

- Aquaporins (channel proteins)-transport water

Question 8

What is Facilitated Diffusion?

Answer 8

-Uses specialised carrier proteins-change conformation in order to move the molecules across the membrane

Question 9

What is the difference between Passive and Facilitated Diffusion?

Answer 9

-Facilitated uses channel/carrier proteins

Question 10

What is Active Transport?

Answer 10

• Transport molecules against concentration gradient so requires energy
• Energy is obtained by the hydrolysis of ATP

Question 11

What is Endocytosis/Pinocytosis (fluid form)

Answer 11

• The drug contacts the plasma membrane
• Vesicle forms around drug and invaginates into plasma membrane.
• The drug is taken in and released

Question 12

What is Saturation Kinetics?

Answer 12

enzyme reaction reaching a maximal velocity at high levels of Substrate

Question 13

What X2 types of diffusion does Saturation Kinetics Effect?

Answer 13

-Facilitated and Passive

Question 14

What are Weak Acids/Bases?

Answer 14

-Weak- Partially dissociate into ions

Question 15

What are Strong Acids/Bases?

Answer 15

-Fully dissociate into ions

Question 16

What determines the form of a drug?

Answer 16

pH of the local compartment

Question 17

What are Acids and Bases?

Answer 17

Acid- Proton Donator ‘a’-away

Base-Proton acceptor

Question 18

What does the Henderson-Hasselbalch Equation calculate?

Answer 18

-Calculates pKa

Question 19

What is the pKa

Answer 19

• The strength of an acid

- Log of Ka (Acid Dislocation constant-a-acid)

Question 20

What is Ka?

Answer 20

-Acid Dissociation constant

Question 21

What is ion trapping?

Answer 21

-Is the trapping of toxins in their ionised form so they cannot be reabsorbed and are excreted from the body.

Question 22

Where do Weak Acids and Bases Accumulate?

Answer 22

-Weak bases-accumulate in compartments of low pH.
-Weak Acids- accumulate in compartments in high pH
(Try balance it out)

Question 23

Name the X5 Body Compartments

Answer 23

-Total Body Water-
-Extracellular Water-
-Blood Plasma-
-Adipose tissue-
Bone and Teeth

Question 24

What is Volume Distribution? (Vd)

Answer 24

• Is how a drug partitions (splits) between plasma and tissue compartments. The pull of drug between blood and tissue.

Question 25

What is Vd used for?

Answer 25

-Calculates drug dosage/volume required

Question 26

What Physiochemical Properties affects the Vd?

Answer 26

( pH and ionisation, method transport, half-life)

Question 27

What samples are taken from volunteers in a trial to calculate the Vd?

Answer 27

-Blood Samples

Question 28

What is the formula for Vd?

Answer 28

Vd=Dose

{Drug}plasma

Question 29

How is {Drug}plasma calculated?

Answer 29

Amount Added/Volume of Beaker

Question 30

Will type of Vd value will require a high drug dosage?

Answer 30

-Higher Vd=High drug dosage

Question 31

What can Plasma Protein binding have an impact on?

Answer 31

-Vd