What is pharmokinetics
how drugs move through the body
What are the steps a drug takes through the body
absorption
distribution
metabolism
excretion
What are the types of absorption
passive diffusion
facilitated diffusion
active transport
endocytosis
What happens in passive diffusion
molecules move from high to low concentration without help
What happens in facilitated diffusion
requires membrane channels to facilitate movement in and out of the cell
What happens in active transport
requires ATP to activate movement
What happens in endocytosis
drug in engulfed in the cell membrane
What affect absorption
pH
surface area
blood flow
What is the equation for bioavailability
AUC oral/ AUC IV *100
What is bioavailability
the proportion of a drug that actually gets absorbed after administration
What affects bioavailabilty
the route of administration
What factors effect distribution
lipophilicity blood flow capillary permeability plasma and tissue binding volume of distribution
What is the lipophiliicity of a drug
lipophilic drugs diffuse through the cell membrane much easier than a hydrophiliic drug
What is an example of how blood flow effects distribution
the brain receives more blood than the skin so if a drug can pass through the blood brain barrier than it will accum more in the brain
What is an example of capillary perm
the livers capillaries are more porous than the brains
What is plasma and tissue binding referign to
how the chemical props of drugs affect what it binds to so some drugs will accumulate in the tissues more or less or bind to proteins like albumin easily
How does binding to albumin effect the distribution
it will signif low it down
Whats the equation for volume of distribution
amount of drug in the body/concentration of drug in the plasma
What is volume of distribution used for
to predict how much the drug will accum in the blood plasma or tissues
What is volume of distribution used for
to predict how much the drug will accum in the blood plasma or tissues
How are most drugs eliminated by
first order kinetics
What is first order kinetics
the rate of elimination is directly proportional to the amount of the drug in the body
Whats an example of first order kinetics
losing at a constant rate like -16% constantly
What is another type of kinetics that drugs can take for elimination
zero order kinetics
What drug takes the zero pathways
aspirin
What is zero order kinetics
rate of elimination is constant
What is an example of zero order kin
losing 200 mg at everytime period so the drug decreases concentration in the body at a constant amount but the percentage of loss changes
What do first order kinetic graphs look like
exponential
What do zero order kin graphs look like
linear
What is half life
the amount of time it takes for there to be half of the amount of drug left
What does a half life help you predict
steady state
What is steady state
the state where the rate of administration= the rate of elimination
Because the kidneys cannot efficiently eliminate lipid soluble drugs so
the liver converts those drugs into water soluble substances
How does the liver convert lipophilic drugs into water soluble ones
through two metabolic reactions called phase I and II
What happens in phase 1
drugs are changed into be more hydrophilic by reactions like reduction oxidation and hydrolysis
What enzyme fam is does most of the reactions in phase 1
cytochrome p450
When does phase two happen
if the drug is still to hydrophilic
What type of reaction happens in phase two
conjugation
What are some conjugation rx that happen in PHase 2
acetylation
sulfation
glutathione conjugation
glucuronidation