Drug Absorption

Question 1

What is pharmaceutical process?

Answer 1

Getting the drug into the patient

Question 2

What is pharmacokinetic process?

Answer 2

Getting the drug to the site of action

Question 3

What is pharmacodynamics process?

Answer 3

Producing the correct pharmacological effect

Question 4

What is therapeutic process?

Answer 4

Producing the correct therapeutic effect

Question 5

What are the 4 basic factors that determine pharmacokinetics?

Answer 5

Absorption

Distribution

Metabolism

Elimination

Question 6

What are different methods of administration?

Answer 6

Oral

Intra-venous (IV)

Subcutaneous (applied under the skin)

Intramuscular

Other GI (sublingual, rectal)

Inhalation

Nasal

Transdermal (delivered across the skin)

Question 7

What is absorption?

Answer 7

Process of movement of unchanged drug from the site of adminstration to the systematic circulation

Question 8

What is the relationship between plasma concentration and the therapeutic response?

Answer 8

There is a correlation between the two

Question 9

What is Cmax?

Answer 9

The peak concentration

Question 10

What is T max?

Answer 10

The time to peak concentration

Question 11

What does the area under the curve of a concentration/time graph represent?

Answer 11

Total amount of drug that reaches systematic circulation

Question 12

What does Tmax tell us?

Answer 12

How quickly the drug is going to get into our circulation to produce an effect

Question 13

What does Cmax tell us?

Answer 13

Whether the effect of a drug may be toxic or ineffective

Question 14

What does increasing the dose do in relation to Tmax and Cmax?

Answer 14

Does not increase Tmax but increases Cmax

Question 15

What is the therapeutic range?

Answer 15

The range of concentration that a drug is active

Question 16

What happens above the therapeutic range?

Answer 16

The drug is toxic

Question 17

What happens below the therapeutic range?

Answer 17

The drug is ineffective

Question 18

What is bioavailability?

Answer 18

The amount of a drug that gets into circulation and is available for biological activity

Question 19

What is the bioavailablity of a drug given intra-venously?

Answer 19

100% bioavailability

Question 20

How is bioavailability determined?

Answer 20

By giving the drug and working out the toal amount over time then comparing this to the IV route

Question 21

What are some factors that affect bioavaiability?

Answer 21

Formulation

Ability of drug to pass physical barriers

Gastrointestinal effects

First pass metabolism

Question 22

What impacts a drugs ability to cross physical barriers?

Answer 22

Particle size

Lipid solubility

pH and ionisation

Question 23

What must a drug be to dissolve in lipids?

Answer 23

Unionised

Question 24

What does first pass metabolism refer to?

Answer 24

Removal of the drug by the liver

Question 25

What is bioavailability used to work out?

Answer 25

The best dosage of a drug for the desired effect

Question 26

What are different kinds of transport across physical barriers?

Answer 26

Passive diffusion Filtration Bulk flow Active transport Facilitated transport Ion-pair transport Endocytosis

Question 27

What does the degree of ionisation depend on for a drug and why?

Answer 27

The environment because most drugs are weak acids or bases

Question 28

When does an unionised drug stop crossing a membrane?

Answer 28

Once equilbrium is reached

Question 29

What may happen whilst a drug is in the middle of crossing a membrane?

Answer 29

Ion trapping

Question 30

What is ion trapping?

Answer 30

Drug crosses the first membrane but then is ionised and cannot cross the second

Question 31

Where do acidic drugs get stick?

Answer 31

In compartments with a high pH

Question 32

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

Answer 32

Lipid-water partition coefficient

Question 33

What must a drug be to diffuse across a lipid membrane?

Answer 33

In solution Lipid soluble

Question 34

What is the lipid-water partition coefficient?

Answer 34

Ratio of the amount of drug which dissolves in the lipid an water phase when they are in contact

Question 35

How are drugs given that cannot diffuse across lipid membranes?

Answer 35

By IV to skip most of these barriers

Question 36

Where does passive diffusion occur?

Answer 36

Along concentration gradients (requires no energy)

Question 37

What does passive diffusion depend on?

Answer 37

Lipid solubility Degree of ionisation

Question 38

Where does facilitated diffusion occur?

Answer 38

Along the concentration gradient but requires carriers

Question 39

What are examples of things that use facilitated diffusion?

Answer 39

Monosaccharides Amino acids Vitamins

Question 40

Where does active transport occur?

Answer 40

Against concentration gradients (requires energy)

Question 41

What are examples of things that use active transport?

Answer 41

Ions such as K, Na and Ca

Question 42

Where does filtration occur?

Answer 42

Through channels in the cell membrane

Question 43

What is the driving force of filtration?

Answer 43

Hydrostatic pressure or osmotic pressure difference across the membrane

Question 44

What uses filtration?

Answer 44

Urea

Question 45

What are gastrointestinal factors that affect drug absorption?

Answer 45

Motility (speed of gastric absorption) Food (can enhance or impair absorption) Illness (can increase or decrease absorption)

Question 46

Where are most drugs absorbed?

Answer 46

Small intestine

Question 47

What is first pass metabolism?

Answer 47

Metabolism of drug prior to reaching systematic cirulation

Question 48

What are some places involved in first pass metabolism?

Answer 48

Gut lumen (acid, enzymes) Gut wall (metabolic enzymes) Liver (hepatic enzymes)

Question 49

What does absorption from subcutaneous/intramuscular sites depend on?

Answer 49

The blood flow at these sites

Question 50

What do drugs given subcutaneously or intramuscularly avoid?

Answer 50

First pass metabolism

Question 51

What do sublingual drugs avoid?

Answer 51

First pass metabolism

Question 52

What is sublingual?

Answer 52

Under the tongue

Question 53

What do drugs given via the rectum bypass?

Answer 53

First pass metabolism

Question 54

What is the absorption of a drug from the rectum like?

Answer 54

Slow

Question 55

What kinds of drugs are often given via the rectum?

Answer 55

Ones that cause irriation to the stomach

Question 56

What is inhalation best for?

Answer 56

Volatile agents

Question 57

How much of an inhalation drug is absorbed?

Answer 57

5-10%

Question 58

What are the advantages of transdermal drugs?

Answer 58

Avoids first pass metabolism and can provide a controlled release

Question 59

What should be considered when deciding the mode of administration?

Answer 59

Purpose and site of drug action Disease effects Patients ability to take medicine Speed of action Reliability of absorption