Lecture 3 Flashcards
Drug distribution
What is Pharmokinetics ?
the life cycle of drugs
What are the diff categories of pharmokinetics ?
- Absorption
2.Distribution
3.Metabolism
4.Excretion
Define Drug Absorption ?
Passage of drugs from site of administration into blood plasma
eg) oral administratiom
What are some factors affectiong drug absorption ?
route of administration
cell membrane permeability
lipid solubility/conc states
endo/exocytosis
conc of drugs
What is lipid solubility and ionization state ?
ionized species have ery low lipid solubility and cell permeability
hydrophobic is more likely to pass through the bilayer
What is ion trapping ?
diff cellualr companants =diff pH
unonized species can equilibrate across membrane while ionized
determined where drug accumalates
Ion trapping with acidic drugs ?
tend to accumalte in compartments with high pH
in stomach
ion trapping in basic drugs?
tend to accumlate in compartments with low pH
What is carrier mediated transport ?
passive diffusion (Ion channels)
fascillitated diffusion( Carrir protein)
Active transport (ATP)
What are some routes of administration ?
intravenous
transdermal
topical
intramuscular
subcutaneous
oral
Why arent all drugs taken orally ?
Taste
incomplete absorption
Destroyed in gut
incomplete release
FIRST PASS METABOLIDM
Define Bioavailability ?
under curve
Measure amount of drug entering general circulation from site of administration
used to compare diff routes of adminstration of a drug and its proportion made available to systemic circulation
What is FIRST PASS METABOLISM ?
anything absorbed by the gut
1st circulation counters
