Pharmacokinetics Flashcards
What is pharmacokinetics?
study of HOW a drug moves through the body
what is pharmacodynamics?
study of a drugs EFFECT at its site of action
what is pharmacogenomics?
study of how our GENOME INFLUCENCES the drugs effect or kinetics in the body
what is the acronym for understanding the mechanisms of how a drug works?
ADME
what does the acronym ADME stand for?
absorption, distribution, metabolism, excretion
what is absorption influenced by the most?
method the drug was introduced to the body and how the drug distributes (IV most bioavailable, oral most common but not as high bioavailability)
what is the partition coefficient?
ratio of octanol/water that determines the hydrophobicity or hydrophilicity of the drug
what are some factors that effect absorption?
concentration of drug/route
regional blood flow
lipophilicity
Surface area/membrane thickness
**smaller non polar absorb best
what is the absorption trend for drugs that are passively absorbed?
the higher the concentration, the more lipid soluble, the lower molecular weight, larger SA, greater regional blood flow =
FASTER DIFFUSION
what is the trend for absorption of drugs that use active transport?
limited absorption because there are only so many receptors/trasporters (increasing dose does not increase concentration)
what are an example of an active transporter that can go against concentration gradient?
P-glycoprotein MDR-1 transporters
(remember these can take the drug that was brought in my one transporter and sent it right back out of the cell)
what is special about diffusion of drugs that use active transport?
these can go against the concentration gradient
if you want a drug to be able to cross the BBB what modification does it need?
needs to be very small and lipid soluble
why cant pregnant women use nicotine?
nicotine can cross the placenta and the fetal liver can not handle it causing harm to the baby
Aspirin has a pKa of 3.5, where will it absorb best?
stomach/early duodenum because that is the most acidic place
if you were to give a drug with a pKa of 13.6 absorb best?
distal small intestine but a drug with a pKa that high would be better to be taken a route other than oral because the stomach acid will mess with its pKa
what is ion trapping?
weak bases get protonated when they cross into the lumen so they can not cross back over, trapping them inside
if a patients urine is too basic how can you help the patient?
give them an acid (too acidic give base)
if a patient takes too much aspirin how can you help increase the clearance of the aspirin?
give them a base
what is bioavailability?
fraction of unchanged drug reaching systemic circulation following administration of any route
how does increasing the bioavailability of a drug shift the PO curve?
shift it up and to the left (to be closer to the IV one which is 100% bioavailable)
why cant ibuprofen be taken with warfarin?
IB will disrupt W binding to albumin which will enhance the anticoagulant effect (warfain is a blood thinner, if it cant thin the blood the patient will be at risk of clot, ib makes it so cant thin, dose if IB is waaaaay more then warfrin so it will bind more, if the warfin is loose could cause toxic effect)
what is the equation for volume of distribution?
amount of drug in body/plasma concentration
how does elimination change for drugs with high volume of distribution?
body needs longer time to eliminate the drug