Flashcards in Topic 2 Deck (19):
What is the final stage of the drug’s time in the body after metabolism
How are drugs usually excreted
via urine or faeces, and sometimes through breath and sweat (and milk).
What does grapefruit juice alter
levels of drugs (increases as though had higher dose)
How does grapefruit juice can alter levels of drugs used to treat allergies/heart disease/infections
through lowering levels of a drug-metabolising enzyme ceased CYP3A4 in the intestines.
What are other substances that have the same effect as grapefruit juice
other juices like Seville (sour) orange juice (but not regular orange juice).
Experiment to test effects of grapefruit/sour orange/regular orange juice
giving participants Plendil, a drug used to treat high blood pressure, in either grapefruit/sour orange/regular orange juice. Found that both grapefruit/sour orange juice increased blood levels of Plendil (as though had a higher dose), while regular orange juice had no effect
What is the chemical in the grapefruit juice that causes the effect
How do furanocoumarins create effect
attach to the enzyme and damaging it so badly that the entire complex disappears from the cell.
What is the main organ responsible for excretion of drugs/other substances from body
What do the kidneys consist of
a collection of tubules through which blood is filtered.
What passes through the kidney tubules
most of the contents of the blood, except for proteins
What happens to substances filtered through kidney tubules
some substances, particularly those that are lipid soluble are absorbed back into the bloodstream through the kidney membrane, while more water-soluble substances are collected together with water and are excreted in the form of urine.
Why is it important to reduce lipid-solubility
so that it can be more water soluble and pass out with water as urine (to facilitate drug excretion)
Can some drugs not be metabolised but still be excreted unchanged in the urine
yes, for example antibiotic penicillin
What properties of drugs make it easier to excrete
decreased lipid solubility; increased molecule size
In general what does metabolism in the liver serve to do
inactivate most drugs
Generally are metabolites more, less or equally lipid soluble compared to original drug
usually less, which facilitates excretion by kidneys
Can metabolites be toxic
yes, e.g. paracetamol overdose