Drug Absorption

Question 1

Define Pharmaceutical process

Answer 1

Get the drug into the patient

Question 2

Define Pharmacokinetic process

Answer 2

Get the drug to the site of action

Question 3

Define Pharmacodynamic process

Answer 3

Produce the correct pharmacological effect

Question 4

Define Therapeutic process

Answer 4

Produce the correct therapeutic effect

Question 5

What determines drug pharmacokinetics

Answer 5

Absorption
Distribution
Metabolism
Elimination

Question 6

What are the methods of administration?

Answer 6

Oral
Subcutaneous 
Intramuscular
Other GI - Sublingual, rectal
Inhalation
Nasal
Transdermal

Question 7

What does absorption involve

Answer 7

Drugs must enter blood stream and distributed to site of action

Question 8

What does ADME allow?

Answer 8

understanding of: 
Dosage 
Drug administration
Drug handling 
Patient variability
Potential for harm.

Question 9

What is sublingual?

Answer 9

Under the tongue

Question 10

Oral absorption

What is Tmax?

Answer 10

The time to peak concentration

Question 11

Oral absorption

What is Cmax?

Answer 11

The peak concentration

Question 12

Oral absorption

What is the (AUC)?

Answer 12

The area under the drug concentration-time curve

Question 13

Does the dose effect the tmax?

Answer 13

No, alters cmax

Question 14

What does the The area under the drug concentration-time curve represent?

Answer 14

The amount of drug which reaches the systemic circulation

Question 15

What is the Therapeutic range?

Answer 15

The range of concentrations at which a drug is active.

Question 16

What happens above or below the therapeutic range

Answer 16

Toxicity

Insufficient/no pharmalogical action

Question 17

What does The AUC allows us to estimate?

Answer 17

BIOAVAILABILITY - extent and rate at which drug reaches systemic circulation.

Question 18

What is the bioavailability of an intravenous drug?

Answer 18

100%

Question 19

What are the factors affecting Bioavailability? (oral absorption)

Answer 19

Formulation

Ability of drug to pass physiological barriers

• Particle size
• Lipid solubility
• pH and ionisation

Gastrointestinal effects
- Gut motility

First pass metabolism

Question 20

What is dissolution?

Answer 20

The rate a drug breaks up

Question 21

What is an example of a physiological barrier?

Answer 21

Transport across membranes

Question 22

What are the methods of transport across membranes?

Answer 22

Passive diffusion
Filtration
Bulk flow
Active transport

Question 23

What does the degree of the ionisation of the drug depend on?

Answer 23

pH of the environment

Question 24

What form of the drug crosses the membrane?

Answer 24

The unionised form

Question 25

What is the distribution of the un-ionised form of a drug?

Answer 25

Distribute across the membrane until equilibrium reached - equal concentration on each side.

Question 26

Where will an acidic drug be most concentrated?

Answer 26

In the compartment with high pH

Question 27

What does the Henderson-Hasselbalch equation describe?

Answer 27

The relationship between the local pH and the degree of ionisation

Question 28

What is The ability of a drug to diffuse across a lipid barrier is expressed as?

Answer 28

lipid-water partition coefficient

Question 29

What is the lipid-water partition coefficient?

Answer 29

The ratio of the amount of drug which dissolves in the lipid and water phase when they are in contact.

Question 30

What factors effect passive diffusion

Answer 30

Molecular size Lipid solubility Polarity Ionisation pH

Question 31

Describe Active Transport in drugs

Answer 31

Energy dependent Against conc gradient drug reversable bound to barrier system

Question 32

What is the structure of drugs that undergo active transport?

Answer 32

They must resemble naturally occurring compounds

Question 33

Describe facilitated diffusion

Answer 33

``` Occurs along the concentration gradient Require carriers Structure specific No energy required ```

Question 34

Where does filtration occur?

Answer 34

Through channels in the cell membrane.

Question 35

What is the molecular size of the drug in Filtration / Bulk Flow/ Pore Transport?

Answer 35

Low molecular size

Question 36

What is the driving force in Filtration / Bulk Flow/ Pore Transport?

Answer 36

Hydrostatic or the osmotic pressure

Question 37

What is first pass metabolism

Answer 37

Metabolism of drug before reaching systemic circulation

Question 38

What can cause first pass metabolism

Answer 38

Limit on oral drug route Gut lumen Gut wall Liver

Question 39

How can first pass metabolism be avoided

Answer 39

Subcutaneous Inhilation Sublingual absorption Transdermal Rectal

Question 40

What does bio phase mean?

Answer 40

The effect site of the drug