week 6 - drug metabolism 1 Flashcards
What is drug metabolism?
the biotransformation (alteration of a substance) of pharmaceutical substances (xenobiotics) in the body
What are xenobiotics?
chemical substances that are not naturally produced or likely present within an organism
What is the major site of metabolic processes of drugs in the body?
the liver
What is drug metabolism?
the IRREVERSIBLE loss of drugs from the body by biochemical conversion
what is a metabolite?
any substance produced during metabolism
What is a pro drug?
It is a biologically inactive compound which can be metabolised in the body to produce a drug
Slide 5
What is bioavailability?
the amount of drug present in the bloodstream
What is first pass metabolism?
It is the metabolism that occurs in the liver prior to the drug reaching the circulatory system.
It can reduce bioavailability - an issue for oral drugs
What makes drugs more water soluble in the body so they can be excreted more readily?
Enzymes with broad selectivity:
cytochrome p450
ethanol
xanthine oxidase
esterases
What is the 2 step process that allows for enzymes too act on drugs to make them more water soluble?
Phase 1 - oxidation, reduction, hydrolysis
Phase 2 - conjugation (attachment of a functional/substituent group)
General features of drug metabolism slide
What does cytochrome p450 do?
It is an enzyme that makes drugs more water soluble so they can be excreted more easily
What does the statement “there is genetic variability in some p450 enzymes” mean?
that some individuals may have genetic variation/mutation in their p450 enzymes.
What can genetic variation in the p450 enzymes result in?
differences in metabolism of certain drugs
reduced excretion and increased toxicity
reduced concentrations of active drug
