distribution/elimination (class) Flashcards
how the drug moves around in the body and gets out of the body
distribution
diffusibility is a function of the ? where solubility is a function of the?
membrane, drug
for a drug to move around fast and efficiently you need high?
diffusibility and solubility
3 things that determine a drugs concentration
- body vs SOA
- duration (how long its in the body)
- Elimination
path through the cell membrane?
stomach –> intestine –> blood stream
what type of molecules will exit the stomach quickly?
small lipid soluble ones
problem with high solubility?
high solubility results in drug molecules aggregating outside the CNS= side effects
3 characteristics of drugs in the CNS
- no discriminability (cant decide where most of the drug goes)
- less “potents” in the CNS
- longer lasting/ annulled effects (annulled because the clean up crew comes in)
why are drugs less “potent” in the CNS
(need less of the drug in the body for the brain to be affected than any other organ , brain is more sensitive)
- the minute you diffuse a drug it will get into the liver before the brain, but you need less of a drug to effect the brain than the liver
capillaries are part of the ? system and allow for the transmission of?
vascular, nutrients
the tightly packed cells of the capillaries allow for? (2)
- minimal transmission across the membrane
2. blood flow affects molecule exit
how does blood flow effect distribution?
the more blood flow the organ receives the more drug it will get
2 types of diffusion through the blood- brain barrier
- active diffusion (ion pump)
2. passive diffusion (transport protein)
active diffusion is a function of the ? where passive diffusion is a function of ?
- body
- drug molecule
passive transport through the BBB is still active for the ? but passive for the ?
active for the brain
passive for the drug
with passive diffusion, the function of the drug molecule depends on (3)
- lipid solubility
- small/ simple chains
- uncharged (not an ion)
- -> can only be ionized after it attaches
the placental barrier is a semi permeable membrane (why?)
the barrier just slows down the rate chemical gets through
–> doe snot stop it
what do maternal blood vessels and blood, fetus capillaries do?
controls the RATE of exchange
2 factors of controlling the rate of exchange in fetus capillaries
- osmotic principles
2. 75-100% of maternal drug in 5 minutes
membrane diffusibility of the placenta will have different effects depending on what?
gestation stage
elimination is dependent on?
intake method
what organ is ALWAYS involved in elimination?
the kidney
organs involved in oral elimination?
liver, kidney
organs involved in parenteral elimination?
kidney
organs involved in absorption elimination?
kidney
organs involved in inhalation elimination?
lung, kidney
what does the liver do?
breaks down drugs in the system and produces the chemicals we need to do so
the liver takes part in ? (2)
- enzyme proliferation
2. “first pass” metabolism
when ppl are tolerant it has to do with? and more of this =
enzymes, more enzymes= less likely the drug will reach SOA
what is “first pass” metabolism
anything that goes mouth, stomach, intestine and out
second pass metabolism is?
anything that goes into the blood stream
3 characteristics of first pass metabolism and the liver
- drug conc is reduced before reaching SOA
- metabolites can be more or less effective than the parent
- excreted (metabolites that are toxins.
what are metabolites?
whats left after the drug is broken down
what metabolism is responsible for side effects
first pass metabolism
elimination is dependent on ?
toxicity of metabolites
characteristics of the drugs not the body
high toxicity= ? order reaction
low toxicity= ? order reaction
- zero
- first
what is zero order reaction
rate of elimination is constant
what is first order reaction
half life elimination
an overdose results in what type of elimination
zero order
an urinalysis tests for? and a blood sample tests for?
- metabolites
- drug
4 problems with drug testing
- detection time < elimination time (drug sample = 48 hours,. urinalysis = 24 hours)
- length of drug use
- individual differences (body comp)
- negative results dont necessarily confirm non- use
why do negative results not always mean they are drug free?
other drugs can interfere (birth control) and genetics (hair colour)
3 characteristics of false negative test
- substitution
- adulteration
- dilution
2 other methods of drug testing
- hair analysis (higher detection period, 90days)
2. oral fluid testing (vulnerable to tampering)
what is a watershed area?
An area where two arteries meet, where blood supply is decreased (border-zone)
what is an example of a watershed area?
internal carotid artery
anterior and middle cerebral artery
carotid artery is extremely dangerous due to?
clotting, changes in BP. bleeding
