Pharmacology: Affinity vs Efficacy

<p>It is a competitive H1 receptor antagonist.</p> Signup and view all the answers

<p>Higher doses decrease the drug's selectivity.</p> Signup and view all the answers

<p>Emax</p> Signup and view all the answers

<p>High potency typically indicates high affinity.</p> Signup and view all the answers

<p>Receptor Reserve</p> Signup and view all the answers

<p>The concentration needed to achieve 50% of the maximal response</p> Signup and view all the answers

<p>Neurotransmitter Levels</p> Signup and view all the answers

<p>The drug's ability to activate the receptor once bound</p> Signup and view all the answers

<p>By both affinity and efficacy</p> Signup and view all the answers

<p>EC50</p> Signup and view all the answers

<p>Antagonist</p> Signup and view all the answers

<p>$10^{-6}$ M</p> Signup and view all the answers

<p>They lie between full agonists and antagonists.</p> Signup and view all the answers

<p>pEC50</p> Signup and view all the answers

<p>Drug A is more potent than Drug D.</p> Signup and view all the answers

<p>Inhibition of ongoing basal activity</p> Signup and view all the answers

<p>On the cell surface</p> Signup and view all the answers

<p>Cardiac contractility</p> Signup and view all the answers

<p>No drugs exhibit complete specificity or selectivity.</p> Signup and view all the answers

<p>Drug's preference for interacting with one target over others</p> Signup and view all the answers

<p>Cytosol</p> Signup and view all the answers

<p>Altered rates of neurotransmitter uptake</p> Signup and view all the answers

<p>Drugs can bind to DNA and cause changes in cellular function.</p> Signup and view all the answers

<p>An approximation of the affinity for the agonist</p> Signup and view all the answers

<p>The concentration producing the maximal response approximates the saturation binding concentration</p> Signup and view all the answers

<p>It typically results in increased apparent potency</p> Signup and view all the answers

<p>Physiological response is not directly proportional to occupancy</p> Signup and view all the answers

<p>Not all receptor sites contribute to the signaling process</p> Signup and view all the answers

<p>Different numbers of receptors available for binding</p> Signup and view all the answers

<p>It reflects binding at 50% of available receptors</p> Signup and view all the answers

<p>Higher receptor sites can still produce maximum responses with small occupancy</p> Signup and view all the answers

<p>The protein undergoes a conformational change, resulting in a pharmacological effect.</p> Signup and view all the answers

<p>Enzymes are usually found in the cytosol of the cell.</p> Signup and view all the answers

<p>Selectivity refers to a drug's ability to preferentially bind to one target subtype over others.</p> Signup and view all the answers

<p>These drugs mainly inhibit the uptake of amine neurotransmitters.</p> Signup and view all the answers

<p>A drug with low affinity can achieve high potency if it has high efficacy, allowing it to produce a significant response even when only a few receptors are occupied.</p> Signup and view all the answers

<p>All drugs have the potential to interact with multiple targets and produce off-target effects.</p> Signup and view all the answers

<p>Dose-response curves allow us to estimate Emax, the maximal response a drug can produce, and EC50 or ED50, the dose necessary for 50% of the maximal response.</p> Signup and view all the answers

<p>They are involved in biochemical metabolic effects that influence various cell functions.</p> Signup and view all the answers

<p>Nuclear receptors reside in the cell nucleus and require drugs to enter the cell to exert their effects.</p> Signup and view all the answers

<p>Receptor reserve can enhance the apparent potency of a drug because even with low receptor occupancy, a maximal response may still be achieved due to spare receptors.</p> Signup and view all the answers

<p>Allosteric modulation can increase a drug's efficacy by enhancing its effect on the receptor, allowing significant responses despite the drug's low binding affinity.</p> Signup and view all the answers

<p>Specificity refers to a drug's unique effect on biological systems, while selectivity is about binding affinity for different targets.</p> Signup and view all the answers

<p>Pharmacokinetic factors and signal amplification can influence drug potency; pharmacokinetics affects drug concentration at the site of action, while signal amplification can enhance the resultant biological effect.</p> Signup and view all the answers

<p>An agonist elicits a tissue response by activating the receptor, while an antagonist binds to the receptor but does not activate it, blocking the effect of the agonist.</p> Signup and view all the answers

<p>$K_A$ is the equilibrium constant for the binding reaction, representing the concentration of drug needed to occupy 50% of the receptors at equilibrium, with lower values indicating higher affinity.</p> Signup and view all the answers

<p>The higher the affinity of a drug for its receptor, the lower the value of $K_A$, indicating that a smaller concentration is needed to occupy receptors.</p> Signup and view all the answers

<p>When the concentration of a drug equals $K_A$, 50% of the available receptors are occupied.</p> Signup and view all the answers

<p>Emax represents the maximum effect that can be expected from a drug.</p> Signup and view all the answers

<p>Receptor antagonists bind to receptors at the same site as agonists but do not activate them, thereby inhibiting the action of agonists and blocking their effects.</p> Signup and view all the answers

<p>As drug concentration increases, the biological response typically shows a graded increase.</p> Signup and view all the answers

<p>Drug binding and receptor activation are reversible and dynamic processes, meaning that drugs can associate and dissociate from receptors over time.</p> Signup and view all the answers

<p>If β equals 0 for an antagonist, it indicates that the binding of the antagonist does not result in any activation of the receptor.</p> Signup and view all the answers

<p>The 'overflow' represents the maximal capability of the cell to increase activity in response to the drug.</p> Signup and view all the answers

<p>Efficacy describes the tendency of the agonist-receptor complex to activate the receptor, with full agonists having high efficacy and partial agonists lower efficacy.</p> Signup and view all the answers

<p>A drug with high binding affinity and a low $K_A$ indicates that only a small concentration of the drug is required to effectively occupy the receptor sites.</p> Signup and view all the answers

<p>A characteristic feature is a graded increase in response with increasing drug concentration.</p> Signup and view all the answers

<p>Understanding this relationship is crucial for determining appropriate dosing and predicting therapeutic effects.</p> Signup and view all the answers

<p>It implies that the drug has no tendency to cause receptor activation and therefore causes no tissue response.</p> Signup and view all the answers

<p>They are often plotted on a semilogarithmic scale, which reveals the relationship between drug dose and response more clearly.</p> Signup and view all the answers

<p>The EC50 value for a partial agonist is a good approximation of its affinity for the receptor.</p> Signup and view all the answers

<p>Concentration-effect curves cannot directly measure affinity since physiological responses are not typically proportional to receptor occupancy.</p> Signup and view all the answers

<p>The concentration that produces the maximal response approximates the saturation binding concentration of the agonist.</p> Signup and view all the answers

<p>A higher receptor reserve usually results in increased apparent potency of full agonists.</p> Signup and view all the answers

<p>Different physiological outcomes can occur when tissues express the same receptor but have different receptor reserve levels.</p> Signup and view all the answers

<p>It suggests that at the EC50 concentration, approximately 50% of the receptor sites are occupied.</p> Signup and view all the answers

<p>The concentration applied may be different from that at the receptor due to factors like distribution and binding dynamics.</p> Signup and view all the answers

<p>Spare receptors play a key role in determining the strength and duration of a drug's effect despite partial occupancy.</p> Signup and view all the answers