midterm Flashcards
pharmacodynamics
effects of a drug on the body
-biochemical and physiologic actions of drugs and mechanisms of drug actions at the molecule, cellular, tissue and organisms level
drugs do not create new functions, but they …..
produce the same action as the body’s own chemicals and they block the action of the body’s own chemicals (when something goes wrong)
what is the importance of a drug receptor
a response results when the drug or ligand binds to its given receptor
-drugs attaches to the sites through varying bonds
what are the most common bonds seen at receptor sites
hydrogen and ionic bonds
-as there is little energy and can be easily broken
two types of receptors
free (unoccupied) or reversibly (occupied)
lock and key model
the receptor is the lock and the drug is the key meaning each drug has to fit into the right receptor
-occurs within the body naturally
induced fit model
the receptor can change the shape slightly meaning the drug does not have to fit exactly
-however, too much change will cause ineffectiveness
functions of ion channels
neurotransmission, cardiac condition and muscle contraction due to different ion channels
-these channels are selective for the ions they conduct
what are the various forms of cell signal
heat, light, water, odors, touch and sound
-remember, without signaling nothing would happen properly
conformational change
when signals from receptor activation/inhibition cause functional or structural changes within the cell
-can cause ion channels to open, formation of intracellular messengers, alterations within gene expressions or alterations in cell growth
agonist
ligand that activates the receptors
-results in an active conformation after the drug has binded to its receptor
-the reaction will occur and will cotninue to occur
antagonists (inhibitors)
preventing the action of the agonist at the receptor site but there is no effect without agonists
-results in inactive conformation after the receptor binds
-stopping of the reaction
what are the subtypes of antagonists
receptor, noncompetitive and competitive
receptor antagonists
can bind to either the active or allosteric receptor site and can be reversible or irreversible
noncompetitive antagonists
can bind to either the active or allosteric site and they are irreversible
-often occur through covalent bonds (which do not easily go away)
competitive antagonists
competes with the agonist for the same receptor site and can block that receptor from binding which maintains its being inactive
-there needs to be an agonsit present, so has to be at an active site
active receptor site
where agonist can bind to cause action
-antagonist will prevent binding of an agonist to the receptor
allosteric site
can be impacted by function
-antagonist will prevent conformational change
therapeutic window
range of doses of a drug that elicits a therapeutic response without adverse effects
-with a smaller window, plasma drug levels must be monitored closely
therapeutic index
what quantifies the therapeutic window
-TD50 / ED50
graded dose response
effects of various drugs on an individual
-potency (affinity of a drug) and efficacy (receptor occupancy of drug molecules) are important parameters
affinity
liking receptors
-the higher affinity, the more likely they will bind to that receptor to produce the effect
quantal dose response
describes the effects of various drug doses on a population
-describes concentrations that produce a given effect in a population
-defined as present or not present
TD50
toxic dose 50% of the time
ED50
effective dose 50% of the time
LD50
lethal dose 50% of the time
ADME
big part of what the body does with the drug consisting of absorption, distribution, metabolism and excretion
-these impact the free drug
absorption
how the drug overcomes obstacles or barriers before a drug can reach its intended target
-needing to get through barriers in order to get into circulation for where the drug is carried where it needs to go
what are some examples of barriers within the body
cell membrane, blood brain barrier, blood labyrinth barrier and the blood placental barrier
factors that impact the ability to cross a cell membrane
lipid solubility, degree of ionization, molecular size and shape of the drug molecule
-more lipid soluble, the easier it will cross
-charged molecules must use a channel
-small molecules can cross easily