Absorption, Distribution, Metabolism, and Elimination Flashcards
What are the key kinetic principles?
- Absorption
- Distribution
- Metabolism
- Excretion/Elimination
What is absorption?
how a drug moves from its site of administration into the bloodstream
What is Distribution?
movement of the drug between blood and tissues
What is metabolism?
conversion of drugs into more hydrophilic metabolites
What is excretion/elimination?
removal of drugs and/or metabolites from the body
What features predict movement of drugs/metabolites?
- molecular size
- degree of ionization
- lipid solubility
- protein binding
To pass through lipid membranes, drugs must be…
non-ionized (uncharged)
To be water soluble, drugs need to be…
ionized (charged)
Most drugs we prescribe are ____ acids or _____ bases
weak acids or weak bases
Strong acids + water do what?
completely goes one way into H+ and conjugate base
Weak acids + water do what?
go both ways from H+ and conjugate base back to the weak acid
What happens with a weak acidic drug in an acidic pH?
non-ionized
protonated
What happens with a weak acidic drug in an basic pH?
ionized
deprotonated
What happens with a weak basic drug in an basic pH?
non-ionized
deprotonated
What happens with a weak basic drug in an acidic pH?
ionized
protonated
Acids are non-ionized (fat soluble) when…
protonated
Acids are ionized (water soluble) when…
deprotonated
Bases are non-ionized when…
deprotonated
Bases are ionized when…
protonated
What is the pKa?
the pH at which there are equal amounts of protonated and non-protonated
When pH=pKa…
protonated equals non-protonated
When pH < (less than) pKa…
protonated form predominates
When pH > (greater than) pKa…
non-protonated form predominates
What is the henderson-hasselbalch equation?