Drug Absorbtion 1

Question 1

Define Pharmaceutical Process?

Answer 1

Getting drug into patient

Question 2

Define pharmacokinetics

Answer 2

Movements of foreign chemicals (xenobiotics) during passage through body
Encompass kinetics of ADME

Question 3

What is pharmacodynamics?

Answer 3

Producing correct Pharmacological effect with drug

Effects of drugs and their action

Question 4

What is the therapeutic process?

Answer 4

Producing intended therapeutic response

(Prevent, diagnose, treat, or relieve symptoms of disease or abnormal condition)

Question 5

What determines pharmacokinetics?
[ADME}

Answer 5

Absorption
Distribution
Metabolism
Elimination

Question 6

Define Absorption:

Answer 6

Process of movement of unchanged drug from site of administration to systemic circulation

Question 7

What are the different drug application routes

Answer 7

Oral
Subcutaneous/Intramuscular
Inhalation/nasal
Transdermal (skin patches)
IV
Topical (creams etc)
Sublingual (under tongue)
Rectal

Question 8

Define therapeutic range:

Answer 8

Dosage range/blood plasma/serum concentration expected to achieve desired therapeutic effect

Question 9

What happens if drug conc. is above or below the therapeutic range?

Answer 9

Above = toxicity
Below = insufficient pharmacological action

Question 10

Define Therapeutic Index (TI):

Answer 10

Comparison of drug conc. level that causes therapeutic effect against amount that causes toxicity

Question 11

What two things must you consider concerning the rate of oral absorption?

Answer 11

Amount of drug entering systemic
Speed at which it happens

Question 12

What is Tmax?

Answer 12

Time till peak drug conc. in systemic circulation

Question 13

What is Cmax?

Answer 13

Peak drug conc. in systemic circulation

Question 14

What is the AUC?

Answer 14

Area under drug conc vs time curve
I.e. amount of drug reaching circulation

Question 15

How does increasing the dose affect Tmax & Cmax?

Answer 15

Increasing Dose = no effect on Tmax but increases Cmax

Question 16

Define Bioavailability?

Answer 16

Amount of Drug reaching circulation & available for action

Question 17

What method of drug administration has 100% bioavailability?

Answer 17

Intravenous (IV) Drugs have 100% bioavailability

Question 18

What 4 factors effect Bioavailability?

Answer 18

• Formulation
• First pass metabolism
• Gastrointestinal effects
• Ability of drug to pass physiological barriers

Question 19

How does formulation affect bioavailability?

Answer 19

Some drugs are prepared for slow release

Question 20

What 3 gastrointestinal effects alter bioavailability?

Answer 20

• Illness & Disease
• Gut Motility
• Food

Question 21

What 3 areas affect the ability of a drug to pass physioloical barriers?

Answer 21

• pH & Ionisation
• Lipid Solubility
• Particle Size

Question 22

Define First pass metabolism?

Answer 22

Amount of drug metabolised by gut before it is absorbed into systemic circulation or reaches site of absorption

Question 23

What does passive diffusion rely on?

Answer 23

Lipid solubility
Degree of ionisation

Question 24

Why does drug ionisation affect passive diffusion?

Answer 24

Only unionised drugs can pass through membranes
Ionised aren’t lipid soluble

Question 25

What does the degree of ionisation rely on?

Answer 25

Local pH i.e. acidic drug will ionise in alkaline environment

Question 26

What is the henderson-hasselbach equation used for?

Answer 26

Relationship between local pH and drug ionisation

Question 27

To what degree do pH changes affect drug ionisation?

Answer 27

Small pH changes cause significant changes to drug ionisation & therefore diffusion rates

Question 28

What is the lipid-water partition coefficient?

Answer 28

Ability of drug to diffuse across lipid barrier Ratio of drug dissolved in lipid vs water phase when in contact

Question 29

Explain active absorption

Answer 29

Active absorption is unusual Occurs against conc. gradient Is specific and requires carriers/energy

Question 30

Example of drugs moved by active absorption

Answer 30

Iron Potassium Sodium Calcium (FeKCaNa) Levodopa uptake by brain (amino acid)

Question 31

Explain Facilitated Diffusion:

Answer 31

Along conc. gradient Needs carriers but not energy Mixed order kinetics

Question 32

Examples of drugs moved by facilitated diffusion:

Answer 32

Monosaccharides AminoAcids Vitamins

Question 33

What drives filtration/bulk flow across membranes?

Answer 33

Hydrostatic or osmotic pressure difference across membrane

Question 34

How does Gut motility affect the rate of drug absorption?

Answer 34

Faster the gastric activity the faster the drug reaches site of absorption

Question 35

What effects can food have on drug absorption?

Answer 35

Food can enhance or impair absorption of some drugs

Question 36

How can illness effect drug absorption?

Answer 36

Malabsorption can impair or enhance drug absorption rates (e.g celiacs disease) (difficulty in digestion or absorption of nutrients from food)

Question 37

How is drug metabolised in first pass metabolism?

Answer 37

Gut lumen - acids/enzymes Gut wall - metabolic enzymes Liver - hepatic enzymes

Question 38

What affects level of first pass metabolism:

Answer 38

Drug Diseases The person

Question 39

Descrive Intravenous drug administration:

Answer 39

- 100% bioavailability - Avoids 1st pass metabolism

Question 40

Describe Topical drug Administration:

Answer 40

- Can achieve local or systemic effects - Can achieve controlled, sustained doses of drugs - Avoids 1st pass metabolism

Question 41

Describe Inhalation drug administration:

Answer 41

- Drug delivered directly to site - Rapid effect - Small doses needed - Reduced adverse effects - Metabolised in lungs, only 5-10% is absorbed (little systemic effect)

Question 42

Describe the Hendersen-Hasselbach equation:

Answer 42

pH = pKa + log10 (ConjugateBase/UndissociatedAcid)