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Flashcards in Topic 2 Deck (19):

An example of drugs interacting with nutrients which impedes their absorption

tetracycline, an antibiotic used to treat antibacterial infections interacts with calcium and magnesium, so if taken with foods that contain these elements (e.g. milk), the antibiotic may not be absorbed and therefore would not be effective.


What barriers do drugs face after surviving the digestive tract

they face cellular barriers that they must cross in order to be absorbed into the bloodstream.


What kind of drug administration routes face cellular barriers

all administration routes, except for intravenous or intra-arterial administration (as they are administered directly into the bloodstream)


Plasma membrane

a protective barriers that is one of the most important regulatory locations in a cell, serving as the point of entry and exit for molecules that are carried to and from the cell via the bloodstream.


How is the plasma membrane often thought of as

as a boundary that distinguishes the living cell from its surroundings and is crucial in keeping cells intact.


What makes up the plasma membrane

it consists of a double layer of fatty or lipid molecules interspersed with protein molecules.


Do different tissues have different thicknesses of cell layers

yes, different tissues have different thicknesses of cell layers


What is the effect of the thickness of cell layers on the rate of passage of the drug

the thicker the layer, the slower the rate of passage of the drug.


What do small gaps within the plasma membrane allow

they allow the passage of small molecules such as water


What is important for molecules that are too large to pass through the small gaps

their lipid solubility (their ability to mix in a fatty solution).


Why is the lipid solubility of large molecules important

due to the lipid nature of the cell membrane


There are also a variety of transport mechanisms within the cell membrane that facilitate

the absorption of molecules


What do the transport mechanisms consist of

protein molecules that function as either carriers that pick up molecules and transport them into the cell, or channels through which the molecules travel.


What happens to the drugs too large to pass through gaps/channels and are not lipid soluble and that cannot be transported by carrier proteins

the amount of drug administered will determine whether enough of the drug is absorbed


What influences the rate of absorption

the rate of absorption is also influenced by the concentration of the drug (the higher the concentration, the greater the rate of absorption)


What is the digestive tract specially designed for

it is specially designed for absorption as this is its major function in the body.


What are features of the digestive tract that facilitate absorption (2)

1) the extensive absorbing area of the intestines; 2) in the stomach, drugs (and food) are broken down to smaller particles


What must happen if a drug is taken in the form of a tablet

it will need to be broken down and dissolved in the stomach before being absorbed.


Where does most absorption of drugs occur

in the small intestine