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33 Cards in this Set
- Front
- Back
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Define drug selectivity
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the ability of a drug to affect one tissue, cell type or organ and not others
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what determines the drug concentration required to form a significant number of drug-receptor complexes
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receptor affinity
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___________ bind to receptors but do not activate them
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antagonists
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what is the role of non-competitive antagonists?
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change the receptor to decrease the efficacy of the binding ligand
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what determines the duration of action of an irreversible antagonist?
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receptor turnover rate
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How do physiological antagonists work?
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2 drugs produce opposite effects through different receptor systems
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Define intrinsic activity. Do competitive antagonists have high or low intrinsic activity?
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extent to which a bound ligand activates a receptor. no intrinsic activity
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Define Vmax
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the point at which a reaction has reached its maximum velocity
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define Km
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the concentration of a substrate required to reach 1/2 Vmax (the measure of the affinity of an enzyme for that specific substrate)
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what is the difference between Kd and Km?
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Kd is the measure of binding, Km is the measure of velocity of a reaction
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what is the equation for the law of mass action?
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[DR] = [D][R] / [D] + Kd
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drug _________ is related to its binding affinity
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potency
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drug __________ is related to the rate and extent of the receptor activation after binding
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efficacy
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what is the equation for drug effect?
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intrinsic activity(alpha) x [DR] (number of occupied receptors)
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what is the equation for Ka?
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1/Kd
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What is Emax?
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the maximum effect on a dose response curve that can be produced (also referred to as efficacy)
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what is EC50?
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The dose concentration at which 50% of the maximal effect is produced (also referred to as potency)
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What is the difference between full and partial agonists?
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full agonists produce a full effect (alpha = 1) partial agonists cannot produce the maximal effect ( 0 < alpha < 1)
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what is the threshold dose?
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the minimal dose required to produce the desired effect
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What does clinical effectiveness depend on?
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a drugs ability to reach the relevant receptors combined with its efficacy
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Label each curve
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which type of antagonist does not require a receptor?
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chemical
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what are the effects of a competitive antagonist on potency and efficacy?
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reduced potency, no effect on maximum efficacy
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what do irreversible competitive antagonists do to ED50?
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no change
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what do irreversible competitive antagonists do to maximum efficacy?
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decrease
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what do non-competitive antagonists do to potency and efficacy?
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decreased efficacy, no change in potency (ED50 remains)
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increased spare receptors have what effect on potency and efficacy?
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efficacy remains the same, potency increases
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What is a graded dose-response curve?
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graph of increasing response to increasing dose
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What is a quantal dose-response curve
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Graph of the fraction of a population that shows a specified response at progressively increasing doses
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What is the LD50
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dose concentration that is lethal for 50% of the population
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What is the therapeutic index?
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LD50/ ED50 (margin of a drug's safety - higher ratio = more safe)
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What is the minimum TI value for a drug to be usable?
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> 1
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What is the certain safety factor?
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LD1 / ED99
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