Exam 1 Quiz 2: Pharmacodynamics Pt 2 Flashcards
study of the physiological and biochemical interaction of drug molecules with cell receptors in target tissue that respond to hormones
pharmacodynamics
receptors
proteins on cell surface or within cells
ligand
chemical or molecule that binds to a receptor with some selectivity
can be a neurotransmitter or a drug
distinct site on the surface of the receptor different from where neurotransmitter binds
- impacts function of the receptor
allosteric binding site
strength of the bond between the drug and the receptor
- how much does the drug like the receptor
binding affinity
drugs ability to alter the activity of the receptor
- what is the drug doing? is there a biological response to the drug?
receptor efficacy
what is receptor efficacy typically compared to
endogenous ligand
- naturally occurring chemical in your body
ex: comparing cocaine to dopamine
has the best chemical fit (highest affinity)
attaches readily to the receptor and produces a significant biological effect
mimic the endogenous ligand
receptor agonist
do receptor agonists always have an excitatory response? explain
no
it depends on the receptor, if the receptor is inhibitory you will get an IPSP
fit receptors but produce no cellular effect (low efficacy)
can prevent active ligands from binding
receptor antagonists
have intermediate efficacy - not a huge effect but still binds
partial agonists
initiate biological action that is opposite to that produced by an agonist
inverse agonist
2 forms of antagonists
competitive and noncompetitive
bind the same site as a neurotransmitter to prevent the neurotransmitter from binding to and activating receptors
competitive antagonists
do NOT prevent neurotransmitter binding
Prevent activation of receptor by binding to other sites
- interacts with endogenous ligand
noncompetitive antagonists
2 types of allosteric regulators and what they are
positive modulators: bind to allosteric sites on receptor and INCREASE the ability of neurotransmitter to bind to and or activate the receptor (amplifies it)
negative modulators: bind to allosteric sites and DECREASE ability of neurotransmitter to bind and or activate receptor (diminishes it - like a whisper)
upregulation vs down regulation
up regulation: inc # of receptors - inc chance of a biological response
down regulation: dec # receptors in response to absence of ligands or chronic activation - dec chance of biological response
dose response curve purpose
how much (dose/amount) of a drug (x-axis) causes a particular effect on the body (y-axis)
smallest dose that produces a measurable effect
threshold dose
amount of drug needed to occupy all receptors (the peak)
maximum response
drug dose that produces on average, a specified all or none response in 50% of the test population
- at what dose do you need to get a response from 50%
ED50 (effective dose 50%)
ED100
dose that produces maximal effect in 100% of he population
how high of a dose do you need to give to reach 100%
toxic dose
TD50
dose at which 50% of the population gets adverse reactions (side effects)
lethal dose
LD50
dose at which 50% of the population die
- not seen for humans usually animals
therapeutic index
TI
TD50/ED50
what range of values can we prescribe with benefits that out weigh the side effects
amount of drug needed to produce a given effect
determined by affinity of drug for receptor and # of receptors available
determined by ED50 value
potency
more potent drugs require____
lower doses to produce the effect
most potent is more to the left on a graph
maximum effect/response a drug can produce what response we are getting
more drug - has no effect - but may inc side effects
highest values on graph = highest
efficacy
what is the purpose of the therapeutic index
calculates drug safety
- provides dose range and accounts for side effects
these can be replaced by an excess of agonist
- replace the endogenous ligand molecule
- shift potency to the right
competitive antagonists
competitive antagonist example
naloxone is competitive antagonist of morphine
- makes it harder to produce the biological response - increases the amount fo drug needed to cause effects
how do noncompetitive antagonists reduce the effects of agonists (3)
- bind to allosteric sites
- disturb cell membrane supporting the receptor
- interfere with cell processes initiated by agonist
change magnitude of biological response
- can effect both potency and efficacy or jus tone or the other
example of a noncompetitive antagonist
want pain relief without the sedative effects
- with these you get as close as possible to pain relief without getting the toxic side effects
- usually given to prevent an overdose
2 drugs interact and reduce effectiveness of both drugs
physiological antagonism
both drugs taken together cause a combined greater effect
additive effects
combination of 2 drugs produces effects greater than the sum of their individual effects
potentiation (drug synergy)
what can a longer half life lead to
accumulatio which increases potential for side effects and toxicity
target therapeutic concentration is achieved only after ____
multiple doses
half life determines the time needed to reach the study state plasma level which is when _____
absorption/distribution phase is equal to the metabolic/excretion phase
