Drug Movement Across Biological Membranes Flashcards
Amphipathic phospholipids are not very permeable to what?
polar (charged molecules)
What part of the phospholipid molecule is the phosphate containing group?
the hydrophilic part (polar head)
What part of the phospholipid molecule is the carbon chain?
the hydrophobic part (non-polar tail)
True or false: Not all polar things are charged, but all charged things are polar.
true
What is the most important mechanism for the passage of drugs across membranes?
passive diffusion
What type of molecules will diffuse through the lipid bilayer?
non-polar molecules
In the oil-water partition coefficient, what would increased polarity be due to?
hydroxyl and amine groups
In the oil-water partition coefficient, what would the decreased polarity be due to?
methyl groups
What does the association constant describe?
the constant relationship between the relative concentrations of protons, the unprotonated acid, and the protonated acid
What is pKa?
the pH at which 50% of the molecule is protonated
What is an acid?
a proton donor
When is an acid in its protonated form?
when there is a proton associated with a weak acid, it is non-ionized, non-charged, and non-polar
In what environment is an acid protonated?
in low pH
What is a base?
a proton acceptor
When is a base in its protonated form?
if there is a proton associated with a weak base, it is ionized, charged, and polar
