Flashcards in Topic 2 Deck (19):
What is an example of a drug that ends up in fat stores
anaesthetic thiopentone (sodium pentothal)
What is anaesthetic thiopentone classified as
ultra-short acting anaesthetic
Why does anaesthetic thiopentone act rapidly
as it is highly lipid soluble so it readily crosses the blood brain barrier where it quickly exerts its anaesthetic effect.
What does the lipid solubility of anaesthetic thiopentone mean in terms of the time of its effect
it also leaves the brain very rapidly with its effects lasting only about 5 minutes, and then it is taken up by fatty tissue in the body and slowly released into the liver where it is metabolised.
How do surgical procedures work around anaesthetic thiopentone lasting shortly
they quickly induce anaesthesia with intravenous thiopentone that acts almost instantaneously, while the more slowly acting agents given by inhalation begin to take over and maintain the anaesthesia for the duration of the surgery
What are other tissues where drugs may be stored
muscle, liver, lungs, fat or bone.
Example of drug being stored in bone
tetracycline antibiotic that has an affinity for calcium and magnesium, may be taken up by teeth and bone, where large amounts of calcium are found (thus not given to young children as it can cause discolouration of the teeth).
What are the tissues and tissue components that serve as reservoirs for drugs
plasma proteins; fat stores; muscle; liver; lung; bone
What happens when the drug is bound up in these stores
they are usually unavailable for action.
What happens while the drug is being distributed throughout the body
breaking down the drug
Can some drugs be metabolised prior to absorption
yes, e.g. alcohol
Where is the main site of metabolism
Where are other sites of metabolism
digestive tract; lungs; blood
What does the liver act like
the body’s chemical processing plant. It is the site of continuous and carefully controlled activity.
Everything that enters the bloodstream (swallowed/injected/inhaled/absorbed through skin/produced by body itself) is carried to where
to the liver
Substances in the liver are chemically transformed by
The liver decreases the what of some drugs