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)
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.