Unit 1 pt 2 Flashcards
pharmacokinetics
what the body does to the drug
phramacodynamics
what the drug does to the body.
what are the 4 steps of pharmacokinetics
- absorption
- distribution
- metabolism
- elimination
what is absorption?
how the drug moves in the system from the point of entry to to the rest of the body.
passive diffusion
when a drug moves from hight to low concentration over a cell membrane.
facilitated diffusion
needs a carrier protein to move a drug from high to low concentration over a cell membrane.
active transport
atp is required to move solutes against their concentration gradient ( low to high concentration)
endocytosis
solutes must be engulfed in a vesicle to enter the cell
exocytosis
solutes must be engulfed in a vesicle to remove the solute from the cell.
how are drugs distributed in to body?
- some bind to albumin in the blood rendering them inactive–> if they increase can lead to toxicity
how is the drug metabolized in the body?
1st pass: fro drugs that enter the enteral route they must go to the liver to be converted into an inactive compound
phase 1: enzymes located in the liver & hydraulic acid break down drug for easy excretion
phase 2: another acid is used to make the durg easier to excrete if phase one is not good enough.
how is drug elimination done in the body?
at the kidneys,
1st order kinetics: drug eliminated at a rate proportional to plasma concentration.
ex: 50%–> 25%–> 12.55
Half life is constant, after each half life the drug concentration is 1/2.
0 order kinetics: drug eliminated a a constant rate no matter how much drug there is.
(half life is not constant and elimination rate is constant)
bioavailability
the amount of the drug that enters circulation chemically unchanged ( %)
ex: IV=100%
loading dose
high therapeutic dose administered quickly or at once before dropping to a lower maintenance dose. ( critical pt)
maintenance dose
keeps an average concentration of drug in system
