Absorption

Question 1

Absorption

Answer 1

The passage of a drug from its site of administration into the plasma

Question 2

To have an effect what must the drug be?

Answer 2

Absorbed into the plasma in sufficient amounts

Question 3

What does the extent of absorption affect?

Answer 3

The therapuetic effect

Question 4

What happens when the concentration of drug is too low?

Answer 4

The effects will be sub therapeutic because there is not enough drug to create an effect on the target site

Question 5

What 5 factors affect absorption?

Answer 5

1. Route of administration 2. Surface area for absorption 3. Blood flow 4. Drug properties 5. Molecular weight

Question 6

Which individual factors affect absorption?

Answer 6

Age, disease, surgery, body composition, hydration status, other drugs taken concurrently

Question 7

How do drugs move across the cell membrane?

Answer 7

From an area of high concentration to an area of low concentration until there is a balance

Question 8

First past metabolism

Answer 8

First-pass metabolism, also known as first-pass effect, refers to the process by which the concentration of a drug is significantly reduced before it reaches the systemic circulation. This occurs primarily in the liver after a drug is absorbed from the gastrointestinal tract (such as when taken orally) and before it reaches the rest of the body.

Question 9

What 3 things affects the rate of absorption?

Answer 9

1. Concentration gradient
2. Surface area for absorption
3. Fat solubility of the drug

Question 10

How do most drugs reach the capillaries? From here what do they do?

Answer 10

Passive diffusion and from here they will travel into the systemic circulation and be distributed around the body

Question 11

What does villi provide?

Answer 11

Large surface area

Question 12

What are fenestrations?

Answer 12

Small holes through which nutrients from blood and drug molecules can pass

Question 13

How are most drugs absorbed?

Answer 13

By passive diffusion across cell membranes

Question 14

What can fat soluble molecules do?

Answer 14

Pass through the cell membrane

Question 15

How are most drugs absorbed?

Answer 15

Through the small intestine into portal circulation

Question 16

What does the liver do?

Answer 16

Destroys a proportion of some orally administered drugs

Question 17

Bio availability

Answer 17

The fraction of an orally administered dose that reaches the systemic circulation as an intact drug

Question 18

What can delay gastric emptying?

Answer 18

Food in the stomach

Question 19

Food and chelation

Answer 19

Food, drink and medication containing calcium (or other metallic ions) can interfere with the absorption of drugs (and iron tablets) via a process called chelation

Question 20

What can affect absorption?

Answer 20

The speed at which the gut moves

Question 21

What happens if the drug is administered at a highly vascular site?

Answer 21

It will join the systemic circulation more quickly

Question 22

Why will a person with HF have poor absorption of oral drugs?

Answer 22

Due to a reduction in splanchnic blood flow (blood flow to the gut)

Question 23

Why do some drugs reach a higher plasma concentration if they are taken after a meal?

Answer 23

Food increases the splanchnic blood flow

Question 24

What can migraine and diabetic neuropathy cause?

Answer 24

Gastric stasis

Question 25

How can the gut impair absorption?

Answer 25

Excessively rapid movement of gut contents like diarrhoea

Question 26

What is acetylcholine?

Answer 26

Is a physiological chemical messenger (neurotransmitter) which regulates the behavior of some organs including the bladder and the gut by acting on the smooth muscle in these organs

Question 27

What does acetylcholine stimulate?

Answer 27

The gut to function- it is an endogenous or natural body chemical

Question 28

What do some drugs do to the gut and how?

Answer 28

Block the muscarinic receptors in the gut from the action of acetylcholine

Question 29

What can migraine cause?

Answer 29

Gastric stasis and reduce absorption of medication

Question 30

Parental drug administration

Answer 30

Refers to any route avoiding the GI tract

Question 31

What happens to a proportion of topical medications?

Answer 31

They are absorbed systemically

Question 32

What can drug absorption be affected by?

Answer 32

The difference between the pH of the drug and the pH of the environment the drug is being adsorbed into

Question 33

What can affect lipid solubility?

Answer 33

pH of the internal environment

Question 34

To be absorbed what drugs must do?

Answer 34

Cross the cell membrane

Question 35

What is lipid solubility affected by?

Answer 35

Ionization

Question 36

What is the degree of ionization affected by?

Answer 36

The nature of the environment (pH)

Question 37

What is the only type of molecules that can cross the cell membrane?

Answer 37

Lipid soluble

Question 38

What type of particles are sufficiently lipid soluble to diffuse across the cell membranes?

Answer 38

Un-charged drug particles

Question 39

What happens to charged molecules?

Answer 39

They are repelled from the cell membranes

Question 40

What can happen to drug molecules when they are an environment with an opposite pH to themselves?

Answer 40

They become charged or ionized

Question 41

What happens to a drug that is weakly acidic in an acidic environment?

Answer 41

Will become unionized and be lipid soluble

Question 42

What happens to a drug that is weakly basic in an acidic environment?

Answer 42

Ionized and water soluble

Question 43

What does this mean will happen to the drug?

Answer 43

It will not be able to cross the cell membranes and cannot be absorbed in an acidic environment

Question 44

Why is pethidine given by injection?

Answer 44

It takes too long for (basic) tablets to reach the higher (more alkaline) pH of the large bowel where they become unionized and lipid soluble again, and can be absorbed

Question 45

What are 5 other terms for polar?

Answer 45

Ionized, charged, water soluble, hydrophilic and lipophobic

Question 46

What are 5 other terms for non polar?

Answer 46

Unionized, uncharged, lipid soluble and hydrophobic