Topic 2 Flashcards Preview

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Flashcards in Topic 2 Deck (16):

Many factors influence distribution, such as

the presence of protein and fat molecules in the blood that bind to the drug molecules and preventing them from reaching their sites of action.


What hurdle do drugs destined for the central nervous system (brain + spinal cord) face

the blood-brain barrier (a nearly impenetrable barricade)


What is the blood-brain barrier

a tightly women mesh of capillaries cemented together to protect the brain from potentially dangerous substances, such as poisons or viruses.


What must drugs be to enter the brain and why

drugs must be lipid soluble as the only means of passage into the brain is through the cell membrane


What happens in some disease states, such as infections of the brain

the capillaries become leaky allowing the entrance of substances normally excluded, such as penicillin


What is the major determinant of how a drug is distributed

its affinity for various tissue components such as fats, proteins or water.


Many drugs are attracted to and bind to what in the blood

proteins in the blood, collectively known as plasma proteins


What effect does drugs binding to plasma proteins have and why

has the effect of trapping the drug in the bloodstream, as plasma proteins are too large to move across or between the cells that make up the blood vessel wall.


What does the limited supply of plasma proteins mean

there is often competition between drugs and those with greater affinity, or more attraction will displace those with lesser affinity for the protein.


What is a key feature of drug distribution

protein binding


Why is it important to know whether a drug has affinity for protein binding

as this influences the effective dose of the drug.


What is a potential source of drug interactions if multiple drugs are taken

protein binding


What does displacement of drugs from proteins do + dangers of this

increases their availability at the sites of action and may result in dangerously high levels that are capable of producing toxic effects.


Why is displacement of drugs dangerous

as it increases their availability at sites of action which may result in dangerously high levels that could produce toxic effects.


As many drugs are lipid soluble, what may happen in the body

they may be attracted to fat stores in the body and during their passage around the body, the drugs may end up in fat stores.


What happens when a drug is in a fat store

it is usually unavailable to exert any effects, but it will tend to exit the body very slowly.