introduction to pharmacokinetics 1

Question 1

what does there need to be for a drug to exert an effective pharmacological effect?

Answer 1

adequate drug concentration at the target tissue

Question 2

drug disposition

Answer 2

process by which a pharmaceutical compound (drug) is absorbed, distributed, metabolized, and excreted within an organism, typically a human or an animal

Question 2

pharmacokinetics

Answer 2

what the body does to the drug

Question 3

pharmacodynamics

Answer 3

what the drug does to the body

Question 4

by what model can drug disposition be described

Answer 4

the ADME model

Question 5

what does ADME stand for

Answer 5

Absorption
Distribution
Metabolism
Elimination

Question 6

how do you define the boundary of what is inside or outside of the body?

Answer 6

The epithelial cell layer defines the boundary of the body
E.g. Digestive and respiratory systems classed as outside the body
A substance is considered Inside the body when the substance has crossed the epithelial barrier into the bloodstream

Question 7

How many different routes of drug administration can youth think of?(name at least 5)

Answer 7

intravitreal
intranasal
intramuscular
transdermal
subcutaneous
transmucosal
intrathecal
epidural
rectal
viginal
and many more…..

Question 8

how do the intestinal walls and the liver serve as barriers?

Answer 8

the intestinal walls and the liver function as the protective barrier to prevent the entry of xenobiotics into the body

Question 9

xenobiotics

Answer 9

foreign substances or chemical compounds that are not naturally produced or expected to be present in an organism’s body

Question 10

formula for bioavailability

Answer 10

Bioavailability (F)= fraction absorbed (fg) * fraction escaping first-pass metabolism (fH)

Question 11

describe the “first-pass effect”

Answer 11

The extent at which a drug is removed by the liver during the first passage into the portal vein through the liver (fraction of dose escaping first-pass effect (fH))

read the following if you want to understand more(it is from chatgpt)

refers to the phenomenon that occurs when a drug is administered orally (by mouth) and is absorbed from the gastrointestinal tract, it enters the hepatic portal circulation (the network of blood vessels that carries blood from the digestive organs to the liver) before entering the systemic circulation (the bloodstream that circulates throughout the body). During this process, the drug is exposed to the liver’s metabolic enzymes before it reaches the systemic circulation. As a result, some drugs are extensively metabolized or transformed by the liver before they can exert their therapeutic effects in other parts of the body.

Question 12

which organ is the first pass effect primarily linked to

Answer 12

the liver

Question 13

what is the bioavailability of an intravenous dose

Answer 13

1 or 100%

Question 14

to measure the bioavailability of a plasma drug on a concentration-time graph, what formula do we use

Answer 14

AUCoral/ AUCintravenous

Question 15

what is bioavailability

Answer 15

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

Question 16

absorption of drugs in terms of bioavailability

Answer 16

Extent intact drug is absorbed from the gut lumen into the portal vein (fraction dose absorbed from gut (fg))

Question 17

cell membranes

Answer 17

the barriers between compartments in the body

Question 18

what does cholesterol affect in cell membranes?

Answer 18

the fluidity and stability of the membrane

Question 19

how do lipophilic molecules cross the cell membrane

Answer 19

they permeate the cell membrane, i.e, they diffuse straight through the lipid bilayer

Question 20

the permeability of lipid molecules through the cell membrane is dependent on?

Answer 20

the concentration gradient of the molecule
partition coefficient

Question 21

solubility in lipids is measured by?

Answer 21

the partition coefficient(Log P)

Question 22

in what phase do lipophilic drugs partition

in what phase do hydrophilic drugs partition

Answer 22

the hydrophobic phase

aqueous phase

Question 23

formula for the partition coefficient

Answer 23

log drug(in the hydrophobic phase)/ log drug (in the aqueous phase)

Question 24

if a drug has a high partition coefficient, then what does that say about it's lipophilicity and permeability

Answer 24

it means that it has a high lipophilicity and permeability

Question 25

partition coefficient

Answer 25

refers to the ratio of drug concentration in each phase(i.e the lipophilic and aqueous phase)

Question 26

match these log P values and their formulations(the formulations have to kinda come from memory icl) 0 0-3 3-4 4-7

Answer 26

injectable oral transdermal toxic(fatty tissues)

Question 27

factors that affect the bioavailability of drugs

Answer 27

solubility instability(for example proteases breaking down insulin in the stomach, if taken orally) first pass effect

Question 28

factors that affect the absorption

Answer 28

pH P-glycoprotein total surface area and contact time blood flow

Question 29

pka

Answer 29

the pH where ionised and unionised forms of the weak acid or base are equal

Question 30

in an acidic environment the unionised form of a weak base predominates, and an ionised form of the weak acid predominates, true or false

Answer 30

false. in an acidic environment, the ionised form of a weak base predominates, and an unionised form of the weak acid predominates

Question 31

in a basic environment, which forms of a weak acid and a weak base predominate?

Answer 31

ionised form of the weak acid predominates and an unionised form of the weak base predominates

Question 32

distribution

Answer 32

refers to the movement of drug molecules from the circulating blood to other areas of the body

Question 33

when is the distribution equilibrium achieved

Answer 33

when the rate of drug entering a tissue/ organ is equal to the rate of removal of drug from a tissue/ organ

Question 34

what is drug distribution rate dependent on

Answer 34

Blood flow Concentration gradient Permeability of cell membranes between compartments (absorption (Log P, pKa) Drug binding to plasma proteins or tissue components

Question 35

drug-protein binding

Answer 35

The readily reversible interactions of drugs with proteins

Question 36

in the drug plasma, what can drugs bind to

Answer 36

Proteins in the plasma Tissue components RBCs

Question 37

albumin mainly binds drugs with what range of pH

Answer 37

an acidic pH so from 0-6

Question 38

can albumin bind to basic drugs sometimes?

Answer 38

yes

Question 39

what are the two well-characterized primary high-affinity binding sites of albumin

Answer 39

sudlow site I and sudlow site II

Question 40

what is site I of albumin also referred to as

Answer 40

warfarin site, because it is where the drug warfarin binds. many other drugs with complementary structural features can also bind to it

Question 41

what is the site II of albumin also known as

Answer 41

the benzodiazepine site

Question 42

volume of distribution

Answer 42

Relates the total amount of drug in the body to the concentration of drug in the plasma

Question 43

what is assumed when calculating the volume of distribution of a drug

Answer 43

we assume that the distribution equilibrium has been achieved

Question 44

formular for the volume of distribution of a drug

Answer 44

total amount of drug in the body(mg)/ plasma drug concentration (mgL^-1)

Question 45

purpose of the volume of distribution

Answer 45

used to calculate what dose should be administered to achieve the therapeutic drug plasma concentration

Question 46

what is the average volume of plasma in humans

Answer 46

2.7L- 3.0L