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Index
»
PHARMACOLOGY 1
»
Chapter 2
»
Level 2
level: Level 2
Questions and Answers List
level questions: Level 2
Question
Answer
pharmacologic potency and maximal efficacy As the concentration of drug increases, its pharmacologic effect also gradually increases until all the receptors are occupied
Graded Dose-Response Relations
• Refers to the concentration or dose of a drug required to produce 50% of that drug's maximal effect.
POTENCY Example: Candesartan (4-32 mg) is more potent than Irbesartan (75-300 mg)
• is the magnitude of response a drug causes when it interacts with a receptor • dependent on the number of drug-receptor complexes formed and the intrinsic activity of the drug
EFFICACY
• crucial for making clinical decisions when LARGE RESPONSE is needed • may be determined by the drug's mode of interaction with receptors
Maximal Efficacy
determining the dose of the drug required to produce a specified magnitude of effect in a LARGE number of individual patients or experimental animals
Quantal Dose-Effect Curves
the dose at which 50% of individuals exhibit the specified QUANTAL EFFECT ED50
Median Effective Dose
the dose required to produce a particular TOXIC EFFECT in 50% of the population TD50
Median Toxic Dose
If the toxic effect is DEATH OF THE ANIMAL LD50
Median Lethal Dose
the ratio of TD50 to the ED50 for some therapeutically relevant effect
Therapeutic Index
Determines the drug's ability to fully or partially activate the receptors
INTRINSIC ACTIVITY
a drug that binds to a receptor and produces a maximal biologic response that mimics the response of the endogenous ligand
Full Agonists
• have intrinsic activities greater than zero but less than one • cannot produce the same maximal efficacy as a full agonist even if all the receptors are occupied • becomes an antagonist if taken concomitantly with a full agonist
Partial Agonists
• have an intrinsic activity less than zero, reverse the activity of receptors, and exert the opposite pharmacological effect of agonist
Inverse Agonists
• bind to a receptor with high affinity but possess zero intrinsic activity
Antagonists
may occur by either blocking the drug's ability to bind to the receptor or by blocking its ability to activate the receptor
Antagonism
PREVENTS an agonist from binding to its receptor and maintains the receptor in its inactive state give example
Competitive Antagonists ex. Terazosin (Norepinephrine)
Partial + Full = __
Antagonist
BIND COVALENTLY to the active site of the receptor, thereby reducing the number of receptors available to the agonist
Irreversible Antagonists
• also causes a DOWNWARD SHIFT of the Emax, with no change in the EC50 value of an agonist • binds to a site (allosteric site) and prevents the receptor from being activated by the agonist • Ex: Picrotoxin in GABA receptors
Allosteric Antagonists
• Physiologic antagonism • an antagonist that may act at a COMPLETELY SEPERATE receptor, initiating effects that are functionally opposite with the agonists
Functional Antagonism