Lee - Pharmacokinetics Flashcards
(52 cards)
pharmacokinetics
what body does to drug
pharmacodynamics
what drug does to body
pharmacogenetics
influence of one gene on drug
pharmacogenomics
influence of entire genome on drug
what are 2 ways to get toxic effects?
drugs going to unintended targets or overdose of therapeutic drugs
spermeation
movement through or around cells which limit size
-drugs have to be of certain size and shape to be absorbed and bind to certain receptors
efficacy
effect of drugs
- same effect b/w 2 drugs –> same efficacy
- nothing to do with []
potency
amount of drug to get an effect
-least concentration –> most potent
what is the best type of drug to give?
one with least potency and takes a higher dose to have effect
-easier to manipulate and regulate
steps in pharmacokinetics
- absorption
- distribution
- metabolism
- excretion
absorption
- polar molecules more easily absorbed (biotransformation in liver)
- no rxn with receptor if bound to carrier
- tight junctions (fast), lipophilic, facilitated or active transport, or endo/exocytosis (slow)
distribution
volume of distribution = amount of drug in body relative to [] in blood - measure space available to house the drug
metabolism
biotransformation by the liver - more polar and water soluble through conjugation to be excreted in urine
- phase 1 and 2 enzymes
- some drugs not metabolized
excretion
- elimination - rate of removal from circulation
- clearance - body’s ability in removing drug
agonist
bind to same site as ligand to have same effect
antagonist
- competitive - binding to same site to block ligand (no response)
- non-competitive - bind to other site to elicit effect
allosteric activator vs. inhibitor
- activator - bind to other receptor site increasing receptor response
- inhibitor - bind to other site decreasing response
partial agonist
sometimes called antagonist
- agonist on its own
- antagonist in presence of other substrate
therapeutic index
Toxic/lethal does divided by effective dose
-bigger number –> better drug
tolerance
down regulating receptors after therapeutic effect takes place
- decrease receptor –> decrease effect
- may have to increase dose
- protective response
barriers to absorption
- cell membrane - small (paracellular; lipophilic (diffuse); hydrophilic and charged (transporter)
- capillaries - easier to get drugs across (larger pores)
- blood/brain - protection; need transporter
- placenta - only lipophilic drugs across
1st pass metabolism
oral –> GI –> hepatic portal vein –> metabolized by liver (protection)
- occurs before interacting with receptor
- can decrease availability in circulation and less reaches active site
- skip by using another method besides oral
- bioavailability good indication
- proteins and lipids have high 1st pass - do not take orally
bioavailability
% of drug that ends up in circulation after 1st pass metabolism
-IV (most) > transdermal > IM and subQ > rectal > oral and inhalation
large, polar, lipophilic drug
do not take orally
- take IV or IM
- harder to be absorbed, 1st pass metabolism, more broken down