Pharmacodynamics Flashcards
what type of name should a veterinarian be familiar with
1) chemical name
2) generic name
3) commercial/trade/brand name
generic name (2)
most drugs act by doing what
stimulating or inhibiting membrane receptors
more than ________ plasma membrane receptors are known, in more than ____ families
1000; 20
in order for a drug to interact with a receptor, it needs to possess adequate (3)
size, charge, shape/anatomic composition
what is the signal transduction pathway
the receptor, cellular target and any intermediary molecules
what is the size range of drugs and why
100-1000
100 MV minimum size for specificity of action
1000 MV maximum size for reasonable movement to sites of action
drugs that interact with receptors through weak bonds are (more/less) selective
more
what is affinity
relative ability to bind to a receptor
the strongest type of bond is _________ which is (more/less) common; the weakest type of bond is _____________, which is (more/less) common; an intermediate type of bond is ___________, which is (more/less) common
covalent, less; hydrophobic, more; electrostatic, more
hydrogen bonds and van der waals bonds are what type of bond
electrostatic
what is the important consequence of enantiomers
one enantiomer is often more potent as it fits the receptor better
drug effect is generally proportional to ____________, which in turn is dependent on ____________
percentage of receptors occupied by the drug; concentration of drug in the ECF
how many mechanisms of transmembrane signalling exist
5
what are the 5 transmembrane signalling mechanisms
1) cytoplasmic receptor (steroids)
2) transmembrane enzyme (tyrosine kinase)
3) transmembrane no enzyme (JAK STAT)
4) ion channel
5) GPCR
what is the most abundant receptor type
GPCR
what is one important GPCR
beta adrenergic receptors
what is the role of second messengers
translate D-R interactions into a change in cellular activity; amplification of signals
T/F most drugs act on receptors that have an endogenous ligand
T
describe the following:
1) agonist
2) partial agonist
3) antagonist
4) inverse agonist
1) fully stimulates the receptor
2) partially stimulates the receptor
3) does not activate receptor; blocks agonists
4) lowers basal activity of receptor
what is the dose response curve
depiction of drug effect as a function of drug concentration
what is potency? what is it defined by
the concentration of drug required to produce a certain effect; half-maximal effective concentration or EC50
what is efficacy? what is it defined by
the magnitude of the cellular response when all receptors of a given type are occupied by the ligand; Emax
T/F the most potent drug is not necessarily the most efficacious
T
is efficacy or potency more important to a clinician
efficacy
what happens to efficacy/potency during competitive receptor antagonism
efficacy does not change (no change in Emax) but potency decreases (EC50 value larger)
what happens to efficacy and potency during non-competitive receptor antagonism
efficacy decreases (Emax is reduced); may or may not see a change in potency (EC50)
what is allosteric antagonism an example of
non-competitive antagonism (will decrease efficacy and may/may not change potency)
what is an example of a positive allosteric modulator
benzodiazepines (increase affinity of GABA receptors for GABA -> muscle relaxation)
what is tolerance
the gradual decrease in responsiveness to chronic drug administration
how does desensitization/tolerance/down-regulation manifest
1) decreased production of receptors
2) phosphorylation of receptor to inactivate
3) sequestration of receptors in the cell
what can happen when a receptor antagonist is used chronically and is suddenly withdrawn
supersensitivity
what is tachyphylaxis
more rapid form of tolerance that can happen on the second dose with some drugs
