general Flashcards
Half life
[ 0.7 x VD ], divided by clearance
time to change concentration of drug in body by one half
Volume of distribution
amount of dug in body / conc drug in plasma
Drugs with high vD
chloroquine, fluoxetine, digoxin, verpamil
Drugs with low vD
anticoags, amoxicillin, diazepam
Clearance
volume of blood cleared of drug per unit time
rate of elimination/concentration of drug
Elimination rate
amount of drug cleared from circulation per unit time
First to zero order kinetics examples
ETOH, aspirin, phenytoin
Zero order kinetics examples
omeprazole, fluoxetine, cisplatin, theophyline
Examples drugs flow dependant elimination
linocaine, propanolol
Extraction ratio
the fraction of drug that is removed from the blood or plasma as it crosses the eliminating organ
clearance/ hepatic blood flow
Drugs high extraction ratio
morphine, propranolol, verapamil, TCA, lidocaine
Drugs low extraction ratio
phenytoin, diazepam, warfarin
Loading dose
(VD x target concentration)/ bioavailability
Highly protein bound drugs
diuretics, phenytoin, valproate, NSAIDs, warfarin, diazepam
EC50
Half maximal effective concentration is a measure of the concentration of a drug, which induces a biological response halfway between the baseline and maximum after a specified exposure time
Therapeutic index
ratio of the dose that exerts toxicity in 50% of the population (TD50) to the dose that exerts a therapeutic or effective response (ED50) in 50% of the population (TI=TD50 / ED50)
Efficacy of a drug
maximal effect a drug will have irrespective of potency/ concentration
Potency
amount of drug needed to produce 50% of maximal effect
Affinity
how tightly a drug binds to receptors
mg 1% of 100ml solution
1000mg
Therapeutic window
Minimum toxic dose-Minimum effective dose. => Range over which we assume drug can be safely used
Kd
Conc for 50% saturation receptors
Inversely proportional to affinity
Dissociation constant
LD50
Dose that would kill 50% test animals
Hormones using cyclic GMP as second messenger
ANP
NO
