Exam 1- Principles, opioids, NSAIDS, GI, antiemetics, respir., antihistamines Flashcards
(172 cards)
pharmacokinetics
what body does to drug
absorb, distribution, metabolism, excretion
pharmacodynamics
what drug actions on target cells
incl. adverse effects
absorption
pharmacokin.
enter body, absorbed into bloodstream
rate of absorp determined by onset of drug
extent determined by intensity or bioavailability of drug
distribution
pharmacokin
drug transp site of action
metabolism
pharmacokin
drug inactiv/biotransformed or changed
excretion
pharmacokin
drug eliminated
absorption rate and extent factors- iv v Po
changes via route
iv- 100%bioaval.
dosage needs be less than oral
oral- <70%, onset 1 hr
Im- onset 15-30min
Subq- onset 30-45min
absorption factors
blood flow site of admin ex. dec circ= dec absorb time GI function (acidity of stomach) Presence food and o/ drugs (can dec absorp) ex. antacids bind to o/ drugs
distribution factors
blood supply protein binding (if binds= inactivated/ effective) dec dosage if protein lvls low BBBarrier pregnancy
distribution intra-cellular transport
lipid pathway (drug dissol in lipid lyr) gated channels (mvmnt ions) carrier proteins
metabolism exceptions- metabolites
metabolites
by-product/ extra step before elimination
active or inactive
can build up and become toxic
metabolism exceptions- prodrugs
ex. codeine
distrib as inactive form
metab. actives
performed via liver
metabolism sites
liver- cytochrome p450 enzymes (cyp)
plasma, RBS’s, lungs, kidneys
hepatotoxicity
can inc exposure active drug
perform liver function test (LFT)
(alanine-aminotransferase) (aspartine-aminotransferase)
if lvls inc= dec dosage
metabolism factors- enzyme induction
enzyme induction
(drugs act. inc production metab. enzymes)
1-3 wks after introduction
dec effectiveness bc dec active form
same drug gets metab by many diff types of enzymes
metabolism factors- enzyme inhibition
dec drug metab enzymes= inc active drug
(in risk toxicity)
Ex. use drug A w/ cyp enzymes and use drug B w/ cyp inhib
drug A not metab as well
metabolism factors- first pass effect
major metab on 1st pass thru liver
dec distrib drug
excretion sites
kidneys, bile/feces
impaired excretion
dec renal function
in risk drug accum
(assoc. w/ unchanged or active drugs)
Excretion factors
blood-uria nitrogen bun inc= dec renal func creatinine byprod musc contraction, inc w/ dec kid. function gfr
minimum effective concentration
mec
baseline lvl before action occurs
toxic conc
lvl which drug causes harm
therapeutic conc.
gap btw b/ extremes
can be monitored
if range narrow drugs prone accum.
assess for peak / trough lvls
peak-drawn after drug given (1hr)
trough- before give drug
(results can alter dosage interval or conc)
serum half-life
time requir drug conc dec 50% determined by rate metab/excretion (if impaired= inc 1/2 life= inc accum; mre prone toxicity) dosage= freq 1/2 life steady state conc.