pharmokinetic
what our body does to meds
pharmokinetic phases
absorption
distribution
metabolism
excretion
drug absorption
drug movement from GI tract into bloodstream
disintegration
breakdown of oral drug into small particles
dissolution
combining small particles w liquid to form soltion
factors affecting absorption
Blood circulation
Pain, stress
Food texture, fat content, temperature
pH
Route of administration
how drugs get from GI tract to liver
via portal vein
bioavailability
how fast drugs get into blood stream
best bioavailability route
IV
best ORAL bioavailability form
liquid
worst bioavailability route
enterocoated meds
first pass effect
drug gets broken down in GI tract and concentration is reduced before it gets into blood stream
how to avoid first pass effect
give meds IV or IM
factors affecting bioavailability
drug form/route
gastric mucosa/motility
giving w food/other meds
change in liver metabolism (bad liver-cant metabolize-stays in system)
primary organ for drug metabolism
liver
are protein bound drugs active or inactive
inactive
are free/not protein bound drugs active or inactive
active
high protein bound drugs are what % bound
over 90%
what part of the drug is active
the unbound part
what happens if u give dilantin (99% bound) and warfarin (90% bound) together
fight for protein and dilantin would push off warfarin (causing warfarin toxicity)
what happens if u dont get enough protein in ur diet
protein bound meds are free and active and u can easially get toxic
half life
how long it takes for 50% of a med to be eliminated
if u give 650mg of a med at 8am and it has a 4h half life, how much is in ur syst at noon
325mg
loading dose
large initial dose of a med w long half life so u get relief faster (digoxin)
whats the main way drugs are excreted
kidney
what happens if the kidneys arent working
cant excrete drug and it builds up in system causing toxicity (monitor BUN, creatinine, GFR)
primary drug effect
desired effect/what its perscribed to do
secondary drug effect
side effecr that can be desireable or undesireable (benadryl also makes u sleepy so give for allergies but also helps sleep)
drug potency
amount of drug needed to elicit a specific physiologic response (high-big response from low dose)
theraputic index (TI)
relationship between therapeutic dose and toxic dose (shows risk for toxicity)
narrow theraputic index
high risk for toxicity (vancomycin, digoxin, dilantin, warfarin)
when do u draw lab to test for peak
1h after giving med
when do u draw lab to test for trough
right before next dose is due (first dose should be out of system)
onset
how long after u give med will u get some effect
peak level
when its at its highest amount (too high-toxic, too low-not working)
duration
how long does med last
trough
lowest blood concentration, draw right before nect dose (high-very likely for toxicity)
agonist
gives u action u want fom med
antagonist
blocks action of something
nonspecific drugs
binds to MULTIPLE SITES
wherever the same type of receptor is, you get same reaction at all those sites (anticholinergics dry up mouth and eyes and retain urine)
nonselective drug
binds to MULTIPLE RECEPTORS
(epinephrine-increase bp/hr, opens airway)
adverse reaction
unintentional and unexpected severe side effect
pharmacogenetics
study of genetic factors influencing indicated resposne
tolerance
decreased response over time
if u take med all the time, eventually effect decreases so u require more
tachyphylaxis
very fast/acute decrease in drug responsiveness
placebo
drug response not expected from drug (pt thinks tylenol makes them drowsy)
drug interaction
alteration of drug effect that occurs inside person
drug incompatability
chemical/physical reaction b/t drugs that occurs in syringe or IV site
drug nutrient
enzymes that work as drug enhancer or inhibitor (grapefruit juice)
drug nutrient enhancer
lower drug effectiveness (ineffective)
drug nutrient inhibitor
increase drug effectivenss (toxicity)
photoallergic
skin reaction caused by light exposure
slower immune mediated response
phototoxic
fast skin reaction caused by light exposure (2-6hrs)
additive
2 meds work together and get combined effect
synergistic
give 2 meds together and get hella strong reaction (more than just 2 combined)
antagonistic
give 2 drugs and one reduces/blocks the effect of the other