Drug Receptor Interactions Flashcards
Approximately how many applications are there for novel drugs every year?
40
What is a novel drug?
entirely new molecular entities
What is the primary source of information regarding the efficacy and safety of new drugs?
drug companies will be the primary source of new information
True or False: All drug targets are neuroreceptors
false
The binding forces involved in drug-receptor interactions are usually a combination of _____ interactions that result in _______ ________.
weak, irreversible binding
What is Kd?
the dissociation constant: the drug concentration required to produce half-maximal occupancy of the receptor population
What is concentration dependence?
the percentage of receptors bound by or occupied by a drug increases as the concentration of that drug increases
What is saturability?
once all of the receptors are bound by a drug, further increases of drug concentration cannot increase the percentage of receptors bound by the drug
What does a small dissociation constant (Kd) mean?
the drug is tightly interacting with its receptor
What is affinity?
the force that impels certain molecules to bind to or unite with certain others to form complexes or compounds
A high affinity drug produces a _____ dissociation constant.
low
What is specificity?
the selectivity of a drug for a particular receptor
What kind of drug has complete specificity?
a drug that binds only on particular drug receptors
What is competitive inhibition of binding?
when two (reversibly binding) drugs which both bind to the same population of receptors are present simultaneously, the two drugs compete to bind to those receptors
How does competitive inhibition of binding effect Kd?
it will appear to increase it (decrease affinity)
What is non-competitive inhibition of binding?
when a drug binds irreversibly to a receptor, other drugs which normally bind to that receptor cannot displace it
What is allosteric modulation of binding?
binding of a drug to a receptor may be increased or decreased by a second drug that does not actually bind to the same site on the receptor
In allosteric modulation of binding, how is the affinity affected?
the total number of receptors is not changed, but the affinity of the receptor for the first drug is changed
What is efficacy?
a percentage of the maximum response that can be mediated by a receptor-effector system (maximum response=complete efficacy)
What is a full agonist?
something that produces the maximum response that can be elicited by those receptors
What is a partial agonist?
something that produces a response, but it is smaller than the maximum response that can be elicited by other agonists at the same receptors
Which is more effective, a full agonist or a partial agonist?
a full agonist
What is an antagonist?
something that binds to the receptor, but does not activate the effector system - blocks activation
What is potency?
a relative measure of drug activity, the concentration (or dose) of a drug required to produce an effect compared with the concentration (or dose) required for other agents to produce the same effect
What is EC50?
the concentration of a drug required to produce 50% of that drug’s maximum response
If there is a low Kd what is the affinity?
high
If there is a low EC50 what is the potency?
high
What does a cumulative dose-response releationship show?
the percentage of patients that reach a certain response threshold at or below that dose
What is ED50?
the effective dose - the dose required to elicit the therapeutic response in 50% of the population
What are the therapeutic effects?
the desired effects
What are the side effects?
the undesired effects
Name 2 scenarios in which side effects can happen.
Sometimes the same receptor that produces the desired therapeutic effect also produces undesired effects
sometimes the drug binds to other targets because the drug is dirty
What is LD50?
the lethal dose in half of the patients
