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Pharmacokinetics
KYCOM Block 9
97
Pharmacology
Graduate
08/09/2013

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Cards

Term
what are the methods of drug input (10)
Definition
oral
buccal
sublingual
rectal
intramuscular
subcutaneous
IV
inhalation
topical
transdermal
Term
oral drugs: benifits (3), downfalls (5)
Definition
benfitis: most common, safest, economical

downfalls: slow, less complete, first pass effect, absorption affected by stomach contants, most absorbed in intestines
Term
buccal drugs: benifits (2), downfalls (1)
Definition
benifits: direct absorption into venous circulation, no first pass

downfalls: fast or slow depending on the drug
Term
sublingual drugs: benifits (2), downfalls (1)
Definition
benifits: direct absorption into venous circulation, no first pass

downfalls: fast or slow depending on the drug
Term
what drugs are commonly siblingual, what are they for
Definition
nitryglocerin: angina
Term
define first pass effect
Definition
drug must first pass through the liver where some is metabolized or less active when it leaves
Term
rectal drugs: benifits (3), downfalls (1)
Definition
benifits: partial escape from first pass, can give higher dose, good for vomiting or nausea

downfalls: can cause irritation
Term
intramuscular drugs: benifits (3)
Definition
fast, complete, can give large volumes
Term
subcutaneous drugs: benifit and downfall
Definition
benefit: large doses ok

downfall: slow absorption
Term
IV drugs: benifits and downfalls
Definition
benifits: bioavaility 100%

downfalls: dangerous because if administration is too rapid, blood levels can become too high
Term
topical drugs: locations, effect radius, downfulls
Definition
skin or mucous membranes
local effects
rate of absorption depends on area but is usually slow
Term
transdermal drugs: benifits (2), downfalls (3)
Definition
benifits: systemic effect, first pass avoidance

downfalls: apply to skin, slow absorption, drug must be potent or the patch has to be huge
Term
what are the three different types of absorption
Definition
passive diffusion
facilitated diffusion
active transport
Term
passive diffusion: power source, MOA, saturatble, specificity
Definition
driven by concentration gradient
ions flow down concentration gradient without a carrier
unable to saturate
low specificity
Term
facilitated diffusion: power source, MOA, saturatble, specificity
Definition
driven by concentration gradient
involves a carrier protein
able to saturate
specific
Term
active transport: power source, MOA, saturatble, specificity
Definition
moves against concentration gradient via ATP
needs carrier proteins
able to saturate
specific
Term
define pKa, what does the number mean if it is high or low
Definition
strength of the acid/base
higher is basic
lower is acidic
Term
how is pKa and pH related mathmatically
Definition
log (A-)/(HA) = pH - pKa for acids

log (B)/(BH+) = pH - pKa for bases
Term
in a sentence relate pH to pKa
Definition
if drug is in pH equal to its pKa, it will be 50% ionized
Term
what type of molecules are most drugs
Definition
weak acids and bases
Term
how is the concentration of a drug that will be ionized on each side of a membrane determined
Definition
pH and pKa which change wether the drug is charged or uncharged
Term
how can drug movement be determined, what is the best mode for a drug to be in for movement
Definition
wether the drug is charged or uncharged, and thus the pH/pKa

uncharged
Term
write the weak acid / weak base ionization equations and explain why they would shift left or right
Definition
BH+ -> B + H+ HA -> A- + H+ shift left when pHpKa equlibrium when pH=pKa
Term
why is a weak base better absorbed in the intestines rather than the stomach
Definition
the intestines are more basic so it will be non-ionized and thus uncharged, allowing bettwer movement and thus absorption
Term
what are physical factors that affect absorption
Definition
blood flow to the absorption site: different in each tissue and body situations

SA for absorption

contact time at the absorption site: during travel drug will get stuck in some areas and go fast through others
Term
define bioavailbility
Definition
fraction that reaches systemic circulation
Term
what is bioavilavility influenced by
Definition
first pass metabolism

solubility of the drug: hydrophillic drugs have less

chemical instability
Term
what are the 4 areas of the plasma curve, explain their boundries and significance
Definition
lag time: time from drug administration to appearance in the blood

onset of activity: time from administration to minimin effective concentration

duration of action: time plasma concentration remains above MEC

elimination: changing elimination of the drug changes its duration of action
Term
if you take an antacid what happens to absorption on the plasma curve for a weak acid and weak base
Definition
donno yet, go look it up
Term
what is distribution of a drug determined by
Definition
size of organ
blood flow
capillay permeability
hydrophobic or hydrophillic drugs (lipid soluble can go more places like CNS)
size of drug: smaller can go through BBB
Term
what is the relationship between drugs and protein binding, why do they do this, what situations, what does it mean for the drug
Definition
most drugs bind to albumin in the blood to hitch a ride because they are lipid soluble

if the drug binds proteins in the tissue compartment it can increase concentration in that compartment
Term
define Vd
Definition
volume distribution

volume of fluid a drug is put into

the volume it would require to contain all the drug in the body at the same concentration in the plasma

relates amount of drug in the body to the plasma concentrations
Term
what is Vd dependent on, give values
Definition
water compartments in the body

plasma 6%
ECF 20% (plasma and IF)
TBW 60%
Term
what does it mean if Vd is larger than TBW
Definition
it rapidly leaves the vascular compartment
Term
how is Vd calculated
Definition
Vd = amount in the body / amount in the blood
Term
what happens to Vd if the drug was not eliminated? if the drug is eliminated? what about graphically
Definition
if not eliminated: the plasma concentration stays the same

if eliminated; the curve is extrpolated to ge the plasma concentration of the drug you need the calculation
Term
how is Vd used, what does it mean if it is big, what other factors is it related to
Definition
tells the amount of drug needed to achieve a desired plasma concentration

large Vd means most of the drug isnt in the extraplasmic space

Vd is related to half life and can extend duration
Term
what are the drug reservoirs (4)
Definition
bound to plasma protein
cellular reserviors
fat
bone
Term
when a drug is bound to a plasma protein that mean the drug structure is like what, what protein is it bound to
Definition
acidic bind albumin and basic bind 1-a-glycoprotein

not hydrophillic or neutral
Term
what does it do to the drug when it binds to a plasma protein
Definition
inactive, cannot cross membranes

dont worry its reversible
Term
what qualifies a tissue to be a cellular reserve, give examples
Definition
if binding of the drug within the cell is reversible, the tissue can be a drug reservior

muscle, ECF, etc
Term
what is cellular reserve in fat not awesome, what types of drugs do this
Definition
it can be a toxin risk in obease people

lipid soluble ones
Term
what drugs accumulate in bones, why is this in particular bad
Definition
tetracyclines, heavy meatals

can cause slow release of toxins like lead over time
Term
what types of drugs enter fetal circulation, by what method
Definition
lipid soluble, non-ionized

simple diffusion
Term
define drug metabolism
Definition
disppearance of a drug by chemically changing it another compound
Term
what normally happens to lipid soluble drugs in metabolism
Definition
absorbed well but removed slow from the body because they are reabsorbed in the renal tubule

drugs are metabolized to a less lipid soluble form to help elimination
Term
metabolism can inactivate drugs: explain this
Definition
drug is metabolized to be biologically inactive, becoming more polar and less lipid soluble

less lipid soluble means less renal reabsorption and more excretion
Term
define prodrug, give two examples, what is an exception that still fits into the prodrug category
Definition
inactive drugs that must be metabolized to activate agents

levodopa
methyldopa

some drugs are active when administered but other parts become active through metabolism (sometimes toxic parts)
Term
some drugs dont need to be metablized, why, what is happening to them
Definition
lithium isnt modified in the body
these drugs act up until the time they are excreted
Term
1st order kinetics of metabolism: laws, definition
Definition
follows michalis-Menten kinetics

rate of drug metabolism is proportional to concentration of free drug

a constant fraction of the drug is metabolized per unit time

enzymes not saturated
Term
zero order kinetics of metabolism: when is it used, what is the law
Definition
drugs with very large doses saturate metaboling enzymes

constant amount of drug metabolized per unit time
Term
phase 1 metabolism: location, main driving reaction / mechanism
Definition
on surface of SER

conversion of lipophillic molecules into polar molecules by adding or unmasking a polar functional group (NH2, OH)
Term
in phase 1 metabolism, once the molecule is polar what happens to it (5)
Definition
cytochrome P450 dependent oxidation
cytochrome P450 independent oxidation
reduction
hydrolysis of esters
hydrolysis of amides
Term
cytochrome p450 dependent oxidation: 4 types and their examples
Definition
hydroxylation: ibprofin, phenytoin

N or O dealkylation: morphine, codeine, caffiene

N or S oxidation: tylenol, nicotine, ametidine

deamination: diazepam, amphetamines
Term
cytochrome p450 independent oxidation: 2 types and their examples. just checking... what does this even have to do with
Definition
amine oxidation: epinepherine

dehydrogenation: ethanol

phase 1 metabolism reaction after conversion into a polar molecule
Term
in phase 1 metabolism give example of a drug that is reduced
Definition
warfarin
Term
in phase 1 metabolism give example of a drug thats ester is hydrolyzed
Definition
asprin, procaine
Term
in phase 1 metabolism give example of a drug thats amide is hydrolyzed
Definition
lidocaine, procalnamide
Term
where does phase 2 metabolism take place, what is the initial reaction that takes place, what is the goal here
Definition
cytoplasm

endogenous substrate is conjugated to the drug increasing the size and decreasing lipophilicity
size keeps it in the kidney tubule helping elimination
Term
what is different in phase 2 metabolism in neonates
Definition
they dont have transferase enzyme so drugs accumulate fast and can be toxic
Term
what reactions occur in phase 2 metabolism (6)
Definition
glucuronidation
sulfation
acetylation
glycine conjugation
glutathione conjugation
methylation
Term
phase 2 metabolism glucuronidation MOA
Definition
addition of glucuronic acid to the drug vua glucuronosyl transferase
Term
phase 2 metabolism sulfation MOA
Definition
adding sulfate to the drug via sulfotransferase
Term
phase 2 metabolism acetylation MOA, why is this reaction different than the others
Definition
add acetyl group to the drug

some people are slow or fast acetylators. slow acetylators are a genotypic variation that can cause lupus)
Term
phase 2 metabolism glycine conjugation MOA and examples
Definition
add glycine to the drug

asprin and niacin
Term
phase 2 metabolism glutathione conjugation MOA and example
Definition
add acetylcysteine to the drug

acetaminophen (toxic metabolite)
Term
phase 2 metabolism methylation MOA
Definition
add methyl group to the drug
Term
name the sites of metabolism (9) intracellular and system levels
Definition
liver, kidney, GI, skin, lungs, SER, cytoplas, mitochondria, cell membrane
Term
where are most drugs metabolized
Definition
the liver
Term
what is a drug metabolizing initiator isoenzyme, what does this mean for the drug in the body
Definition
makes you less able to metabolize drugs. adding drug will give side effects stopping drug from being broken down
Term
drug metabolizing initiator examples
Definition
cimetidine, erythromycin, ketonasole, grape fruit
Term
what is a drug metabolizing inducer isoenzyme, what does this mean clinically
Definition
increase production of enzymes via gene expression
make plasma levels lower via more enzymes
you may need to increase dose if they are on an inducer
Term
give examples of drug metabolizing indicers and their MOA
Definition
bensopyrine: p460 1As family in the liver

chronic ethanol: p450 2E1 family

phenytoin, carbamepine, rifampin, barbituates: p450 3A4 family
Term
what are the drugs that follow zero order kinetics, under what conditions
Definition
asprin, ethanol, penytoin

when in high dose, except ethanol
Term
what determines the interaction of a drug
Definition
rate of elimination and dosage
Term
what is the relationship between elmination and excretion
Definition
there is none, drug can be eliminated by metabolism before excretion
Term
how is a drug eliminated if it is not metabolized
Definition
excretion
Term
where are the areas in the kidney excretion occur
Definition
glomerulus, PCT, DCT
Term
what types of drugs are filtered in the glomerulus
Definition
free unbound
filter by size, not by pH or solubility
Term
what drugs are filtered in the PCT, how
Definition
drugs not filtered in the glomerulus that pass into capillary plexus

active transport for specific anions (deprotinated WA) and cations (protinated WB)
Term
how does PCT drug excretion cause hypernatremia
Definition
drug is WA and competes for uric acid in PCT causing side effects
Term
what is the down side of PCT filtration
Definition
low specificity, drugs can compete for carriers

incompletely developed in infants and neonates can cause toxicity due to inability to eliminate
Term
explain how DCT reabsorption works
Definition
drug concentration now increases that of the perivascular space

if uncharged the drug back diffuse back into circulation

you can manipulate pH of urine do decrease reabsorption and increase elimination. increase percent of drug ionizationed form
Term
define ion trapping
Definition
acidify urine traps protonated weak bases increasing their clearance
Term
how is clearance calculated
Definition
rate of elimination of te drug / plasma drug concentration
Term
how is rate of elimination calculated
Definition
CL x Cp
Term
how is clearence altered
Definition
disease, age, other
Term
what is excreted in the GI
Definition
poo

drugs orally administered and not absorbed

MW > 300
Term
what is excreted in the pulmonary
Definition
anesthetics
alcohol
Term
what is excreted in milk
Definition
highly lipid soluble drugs
Term
give 5 examples of drugs secreted in milk
Definition
barbituates, salicylates, morphine, steroids, radioactive substances
Term
what is half life not affected by
Definition
constant infusion, injection, or oral if the drug is eliminated by 1st order kinetics
Term
what is half life affected by
Definition
clearance which is easily changed too
Term
how os half live calculated
Definition
t1/2 = (0.7 x Vd) /CL
Term
increased half life
Definition
diminished renal plasma flow
renal disease
decreased metabolism
Term
what causes deminished plasma renal flow
Definition
cardiogenic shock, heart failure, hemorrhage
Term
what causes decreased metabolism
Definition
cytochrome p45o inhibitor
hepatic insufficiency
cirrhosis
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