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

A knowledge of the factors of pharmacokinetics enables an understanding of what?

Answer 6

Dosage

Drug administration

Drug handling

Patient variability

Potential for harm

Question 7

What must most drugs do to have biological action?

Answer 7

Enter the blood stream and be distributed to a site of action

Question 8

What are different methods of administration?

Answer 8

Oral

Intra-venous (IV)

Subcutaneous (applied under the skin)

Intramuscular

Other GI (sublingual, rectal)

Inhalation

Nasal

Transdermal (delivered across the skin)

Question 9

What is absorption?

Answer 9

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

Question 10

What does absorption depend on?

Answer 10

Properties of the drug

Dosage used

Anatomy and physiology of the drug absorption site

Question 11

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

Answer 11

There is a correlation between the two

Question 12

What is Cmax?

Answer 12

The peak concentration

Question 13

What is T max?

Answer 13

The time to peak concentration

Question 14

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

Answer 14

Total amount of drug that reaches systematic circulation

Question 15

What does Tmax tell us?

Answer 15

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

Question 16

What does Cmax tell us?

Answer 16

Whether the effect of a drug may be toxic or ineffective

Question 17

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

Answer 17

Does not increase Tmax but increases Cmax

Question 18

What is the therapeutic range?

Answer 18

The range of concentration that a drug is active

Question 19

What happens above the therapeutic range?

Answer 19

The drug is toxic

Question 20

What happens below the therapeutic range?

Answer 20

The drug is ineffective

Question 21

What is bioavailability?

Answer 21

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

Question 22

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

Answer 22

100% bioavailability

Question 23

How is bioavailability determined?

Answer 23

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

Question 24

What are some factors that affect bioavaiability?

Answer 24

Formulation

Ability of drug to pass physical barriers

Gastrointestinal effects

First pass metabolism

Question 25

What impacts a drugs ability to cross physical barriers?

Answer 25

Particle size Lipid solubility pH and ionisation

Question 26

What must a drug be to dissolve in lipids?

Answer 26

Unionised

Question 27

What does first pass metabolism refer to?

Answer 27

Removal of the drug by the liver

Question 28

What is bioavailability used to work out?

Answer 28

The best dosage of a drug for the desired effect

Question 29

What are different kinds of transport across physical barriers?

Answer 29

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

Question 30

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

Answer 30

The environment because most drugs are weak acids or bases

Question 31

When does an unionised drug stop crossing a membrane?

Answer 31

Once equilbrium is reached

Question 32

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

Answer 32

Ion trapping

Question 33

What is ion trapping?

Answer 33

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

Question 34

Where do acidic drugs get stick?

Answer 34

In compartments with a high pH

Question 35

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

Answer 35

Lipid-water partition coefficient

Question 36

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

Answer 36

In solution Lipid soluble

Question 37

What is the lipid-water partition coefficient?

Answer 37

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

Question 38

How are drugs given that cannot diffuse across lipid membranes?

Answer 38

By IV to skip most of these barriers

Question 39

Where does passive diffusion occur?

Answer 39

Along concentration gradients (requires no energy)

Question 40

What does passive diffusion depend on?

Answer 40

Lipid solubility Degree of ionisation

Question 41

Where does facilitated diffusion occur?

Answer 41

Along the concentration gradient but requires carriers

Question 42

What are examples of things that use facilitated diffusion?

Answer 42

Monosaccharides Amino acids Vitamins

Question 43

Where does active transport occur?

Answer 43

Against concentration gradients (requires energy)

Question 44

What are examples of things that use active transport?

Answer 44

Ions such as K, Na and Ca

Question 45

Where does filtration occur?

Answer 45

Through channels in the cell membrane

Question 46

What is the driving force of filtration?

Answer 46

Hydrostatic pressure or osmotic pressure difference across the membrane

Question 47

What uses filtration?

Answer 47

Urea

Question 48

What are gastrointestinal factors that affect drug absorption?

Answer 48

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

Question 49

Where are most drugs absorbed?

Answer 49

Small intestine

Question 50

What is first pass metabolism?

Answer 50

Metabolism of drug prior to reaching systematic cirulation

Question 51

What are some places involved in first pass metabolism?

Answer 51

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

Question 52

What does absorption from subcutaneous/intramuscular sites depend on?

Answer 52

The blood flow at these sites

Question 53

What do drugs given subcutaneously or intramuscularly avoid?

Answer 53

First pass metabolism

Question 54

What do sublingual drugs avoid?

Answer 54

First pass metabolism

Question 55

What is sublingual?

Answer 55

Under the tongue

Question 56

What do drugs given via the rectum bypass?

Answer 56

First pass metabolism

Question 57

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

Answer 57

Slow

Question 58

What kinds of drugs are often given via the rectum?

Answer 58

Ones that cause irriation to the stomach

Question 59

What is inhalation best for?

Answer 59

Volatile agents

Question 60

How much of an inhalation drug is absorbed?

Answer 60

5-10%

Question 61

What are the advantages of transdermal drugs?

Answer 61

Avoids first pass metabolism and can provide a controlled release

Question 62

What should be considered when deciding the mode of administration?

Answer 62

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