Lee - Pharmacokinetics Flashcards
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