ANTAGONISTS 2 Flashcards
WHAT IS THE KD MEASURING
THE BACK REACTION/FORWARD REACTION
WHAT RELATIONSHIP DOES THE KD HAVE WITH AFFINITY
INVERSE RELATIONSHIP
THE SMALLER THE KD THE HIGHER THE AFFINITY
WHAT IS THE TERM USED TO DESCRIBE THE CONCENTRATION OF DRUG IT TAKES TO OCCUPY 50% OF RECEPTORS
KD
WHY DO WE MEASURE RECEPTORS
TO DEFINE RECEPTORS
TO UNDERSTAND THE RATE OF LIGAND DRUG ACTION
TO FIND HOW MANY RECEPTORS ARE IN A GIVEN TISSUE
TO FIND HOW RECEPTOR NUMBERS CHANGE IN DISEASE
WHAT IS EC50
THE EFFECTIVE CONCENTRATION GIVING 50% MAXIMAL RESPONSE
WHAT IS A RECEPTOR RESERVE
MORE RECEPTORS EXIST THAN ARE NEEDED, IN THIS WAY NOT ALL RECEPTORS NEED TO BE OCCUPIED TO GIVE A MAXIMUM RESPONSE
WHAT PERCENTAGE OF RECEPTORS IN THE GUT ARE RESERVE RECEPTORS
95%
ON WHAT KIND OF DATA IS THE HILL EQUATION USED
CONCENTRATION RESPONSE CURVE
WHEN MEASURED AGAINST OTHER DRUGS, THE DRUG WITH THE LOWEST EC50 IS CONSIDERED TO BE MOST ………..
POTENT
THE POTENCY OF AN AGONIST DEPENDS ON WHAT 3 FACTORS
AFFINITY, EFFICACY AND SPARE RECEPTORS
WHAT EFFICACY DOES AN AGONIST HAVE
1
WHAT EFFICACY DOES A PARTIAL AGONIST HAVE
<1
FOR A PARTIAL AGONIST, IN ORDER TO ELICIT A MAXIMUM RESPONSE THAT THE SPECIFIC DRUG IS CAPABLE OF, WHAT OCCUPANCY MUST IT HAVE
100%
SINCE 100% OCCUPANCY IS REQUIRED FOR A SPECIFIC DRUG MAXIMUM WHEN THE DRUG IS A PARTIAL AGONIST, WHAT CAN BE SAID ABOUT KD
KD=EC50
FOR A PARTIAL AGONIST WHERE KD=EC50, WHAT DOES THIS MEAN FOR ACQUIRING THE AFFINITY
YOU CAN USE A DOSE RESPONSE CURVE TO ACQUIRE THE AFFINITY OF A PARTIAL AGONIST
WHAT DETERMINES THE EFFECT OF A DRUG IN A LIVING SYSTEM
SPECIFICITY
AFFINITY
EFFICACY
WHAT IS ANTAGONISM
A DRUG THAT PREVENTS THE RESPONSE OF AN AGONIST
WHAT ARE THE 5 CLASSES OF ANTAGONISM
- CHEMICAL
- PHARMACOKINETIC
- PHYSIOLOGICAL
- NON COMPETITIVE
- COMPETITIVE BY RECEPTOR BLOCK
WHAT IS CHEMCAL ANTAGONISM
SUBSTANCES COMBINE IN SOLUTION SO THE EFFECTS OF THE DRUG ARE LOST
WHAT IS PHARMACOKINETIC ANTAGONISM
REDUCES THE AMOUNT OF ACTIVE DRUG BY CHANGING ABSORPTION, METABOLISM, CONSTIPATION
WHAT IS PHYSIOLOGICAL ANTAGONISM
WHEN ONE DRUG ACTION COUNTERACTS ANOTHER DRUG ACTION
WHAT IS NON COMPETITIVE ANTAGONISM
PREVENTS THE ACTION OF AN AGONIST BY ACTING DOWNSTREAM OF THE BINDING SITE OR IN A LOCATION OTHER THAN THE BINDING SITE
WHAT IS COMPETITIVE ANTAGONISM BY RECEPTOR BLOCK
WORKS AT THE SAME SITE AS THE AGONIST TO REDUCE OCCUPANCY OF THE AGONIST
HOW CAN COMPETITIVE ANTAGONISM BE OVERCOME
INCREASE THE CONC OF THE AGONIST TO REOCCUPY RECEPTOR AND DISPLACE THE ANTAGONIST
GIVE AN EXAMPLE OF CHEMICAL ANTAGONISM
CHELATING AGENTS BIND TO HEAVY METALS TO INACTIVATE THEM
GIVE AN EXAMPLE OF PHARMACOKINETIC ANTAGONISM
DIURETICS INCREASE URINATION THEREBY DECREASING THE CONC OF DRUG AS LOST IN URINE
GIVE AN EXAMPLE OF PHYSIOLOGICAL ANTAGONISM
BRONCHODILATORS ARE COUNTERACTED BY BRONCHOCONSTRICTORS
IN WHAT CASE COULD COMPETITIVE ANTAGONISM NOT BE OVERCOME
IF THE ANTAGONIST IS IRREVERSIBLE
WHAT WOULD A CONCENTRATION RESPONSE CURVE LOOK LIKE FOR AN IRREVERSIBLE COMPETITIVE ANTAGONIST
MAXIMUM RESPONSE WILL ONLY BE ACHIEVED AS LONG AS THERE IS A RECEPTOR RESERVE BUT THIS IS TIME CONC DEPENDENT
WE CAN MEASURE THE SHIFT OF A DOSE RESPONSE CURVE AT DIFFERENT CONCENTRATIONS OF AN ANTAGONIST ADDED TO AN AGONIST – WHAT IS THIS CALLED AND HOW IS IT CALCULATED
DOSE RATIO = CONC OF AGONIST IN PRESENCE OF ANTAGONIST/ CONC OF AGONIST IN ABSENCE OF ANTAGONIST
WHAT EQUATION CAN SHOW THE RELATIONSHIP OF ANTAGONIST AFFINITY, DR AND AGONIST CONC.
DOSE RATIO = ([ANTAGONIST]/KD)+1
WHAT IS A SCHILD ANALYSIS
THE RELATIONSHIP OF ANTAGONIST AFFINITY, DR AND AGONIST CONC.
TO PLOT A SCHILD GRAPH, WHAT DR DO WE USE
DR=2
WHAT AXES ARE ON A SCHILD GRAPH
LOG(ANTAGONIST) AGAINST LOG(DR-1)
WHAT HAPPENS IN THE CASE OF IRREVERSIBLE COMPETITIVE ANTAGONISM
THE ANTAGONIST FORMS A COVALENT BOND AT THE RECEPTOR SITE
THE POINT AT WHICH THE LINE CROSSES THE X AXIS IS CALLED WHAT
PA2
WHAT DOES THE PA2 REPRESENT
A MEASURE OF AFFINITY - THE MOLAR CONCENTRATION OF ANTAGONIST THAT GIVES A DOSE RATIO OF 2
WHAT IS THE PA2 EQUAL TO
-1LOGKD
WHY MIGHT DESENSITISATION OCCUR
WHEN GIVEN CONTINUOUSLY OR REPEATEDLY
- LOSS OF RECEPTORS FROM THE SURFACE
- CHANGE IN THE RECEPTOR ITSELF
- EXHAUSTION OF MEDIATORS
- INCREASED METABOLIC DEGRADATION/EXTRUSION OF DRUG
- PHYSIOLOGICAL ADAPTATION
