Drug Absorption

Question 1

What is pharmacokinetics?

Answer 1

What the body does to the drug (metabolism etc)

Question 2

What does ADME stand for?

Answer 2

Absorption
Distribution
Metabolism
Excretion

Question 3

What is absorption?

Answer 3

Process by which unchanged drugs enter the circulation

Question 4

What is distribution?

Answer 4

Dispersion or a drug among fluids and tissues of the body

Question 5

What is metabolism?

Answer 5

Transformation of a drug into daughter compounds

Question 6

What is excretion?

Answer 6

Removal of drugs/ metabolites from the body

Question 7

Why is ADME important (5)?

Answer 7

Safe and intelligent use of medicines by all doctors 
Designing dose regimens
Monitoring treatment compliance
Medicine licensing requirement
Substance abuse monitoring

Question 8

What does the choice of delivery rate depend on (4)?

Answer 8

Speed of onset
Convenience
Bioavailability
Side effects/ specificity of action

Question 9

What is bioavailability?

Answer 9

Proportion of administered drug reaching the system circulation

Question 10

What is the bioavailability for IV drugs?

Answer 10

100%

Question 11

What are the routes of administration?

Answer 11

Oral

IV

Question 12

What are the three options of delivery for IV drugs?

Answer 12

Subcutaneous
Intramuscular
Intravenous

Question 13

Where is subcutaneous IV?

Answer 13

Under the epithelium

Question 14

Where is intramuscular IV?

Answer 14

In the muscle

Question 15

Where is Intravenous IV?

Answer 15

Into the blood vessel

Question 16

What is the BAR availability of drugs?

Answer 16

Amount of drugs to reach the bloodstream

Question 17

What is transcellular?

Answer 17

Through cells

Question 18

What is paracellular?

Answer 18

Between cells

Question 19

How can drug absorption occur?

Answer 19

Active transport through cells
Facilitated diffusion through cells
Passive diffusion

Question 20

What is ficks law?

Answer 20

Rate of diffusion = surface area x concentration difference x permeability

Question 21

What is drug permeability governed by?

Answer 21

Molecular size, lipid solubility and presence of charged or ionisable groups

Question 22

What does the extent of drug ionisation depend on?

Answer 22

pH of environment and the acid/ base dissociation constant of the drug

Question 23

What must drugs be to diffuse across cell membranes?

Answer 23

Uncharged

Question 24

What drugs are absorbed most effectively?

Answer 24

Nonionisable, lipophilic drugs

Question 25

What do the Henderson-hasselbalch equations do?

Answer 25

Predict the extent of ionisation

Question 26

In the Henderson-hasselbalch equations, when does pH=pKa?

Answer 26

When drug is 50% ionised

Question 27

What will happen to acidic drugs when the pH decreases?

Answer 27

More unionised

Question 28

What will happen to alkali drugs when the pH increases?

Answer 28

More unionised

Question 29

Is aspirin acidic or basic?

Answer 29

Weak acid

Question 30

What form is aspirin in in the stomach?

Answer 30

Unionised

Question 31

How can aspirin not move back from bloodstream to stomach?

Answer 31

Once it is absorbed into the bloodstream, it ionises so it can’t be reabsorbed

Question 32

What is ion trapping?

Answer 32

Acidic drugs are absorbed efficiently into stomach whereas basic drugs aren’t and give versa

Question 33

Where do oral basic drugs get absorbed into the bloodstream?

Answer 33

In the intestine, where the surface area compensates for low absorbance efficiency

Question 34

What are the lipinski rules?

Answer 34

A set of rules that help to determine specific properties of a developing drug

Question 35

Give the lipinski rules

Answer 35

Molecular weight <500Da No more than 5 h-bond donors No more than 10 h-bond acceptors LogP<5 (partition coefficient)