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37 Cards in this Set
- Front
- Back
• Pharmacodynamics is the study of:
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the biochemical and physiologic effects of drugs and the molecular mechanisms by which those effects are produced.
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• For most drugs, the dose-response relationship is graded. This means:
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the response gets more intense with increasing dosage.
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• Maximal efficacy is defined as:
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the biggest effect a drug can produce.
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• Although efficacy is important, there are many situations in which a drug with relatively low efficacy is:
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preferable to a drug with very high efficacy.
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• A potent drug is simply a drug that:
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produces its effects at low doses. As a rule, potency is not important
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• Potency and efficacy are independent qualities.
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Drug A can be more effective than drug B even though drug B may be more potent. Also, drugs A and B can be equally effective, although one may be more potent than the other.
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• A receptor can be defined as:
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any functional macromolecule in a cell to which a drug binds to produce its effects
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• Binding of drugs to their receptors is:
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almost always reversible
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• The receptors through which drugs act are:
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normal points of control for physiologic processes.
Under physiologic conditions, receptor function is regulated by molecules supplied by the body |
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• All that drugs can do at receptors is:
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mimic or block the action of the body’s own regulatory molecules
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• Because drug action is limited to:
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mimicking or blocking the body’s own regulatory molecules, drugs cannot give cells new functions.
Rather, drugs can only alter the rate of pre-existing processes |
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There are four primary families of receptors:
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cell membrane-embedded enzymes, ligand-gated ion channels,
G protein-coupled receptor systems, and transcription factors |
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• Receptors make selective drug action possible, therefore:
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If a drug interacts with only one type of receptor, and if that receptor type regulates just a few processes, then the effects of the drug will be relatively selective.
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• If a drug interacts with only one type of receptor, but that receptor type regulates multiple processes, then:
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the effects of the drug will be nonselective
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If a drug interacts with multiple receptors
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its effects will be nonselective.
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Selectivity does not guarantee:
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safety.
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The term affinity refers to :
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the strength of the attraction between a drug and its receptor
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• Drugs with high affinity have:
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high relative potency.
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• The term intrinsic activity refers to:
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the ability of a drug to activate receptors.
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• Drugs with high intrinsic activity have:
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high maximal efficacy.
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• Agonists are:
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molecules that activate receptors
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• In terms of the modified occupancy theory, agonists have:
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both affinity and high intrinsic activity. Affinity allows them to bind to receptors, whereas intrinsic activity allows them to activate the receptor after binding.
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• Antagonists are drugs that:
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prevent receptor activation by endogenous regulatory molecules and by other drugs.
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• Antagonists can be subdivided into two major classes:
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(1) noncompetitive antagonists and
(2) competitive antagonists. Most antagonists are competitive. |
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• Noncompetitive antagonists bind:
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irreversibly to receptors.
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• Competitive antagonists bind:
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reversibly to receptors.
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• In terms of the modified occupancy theory, antagonists have:
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affinity for receptors but no intrinsic activity. Affinity allows the antagonist to bind to receptors, but lack of intrinsic activity prevents the bound antagonist from causing receptor activation.
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• Antagonists have no observable effects in the absence of:
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agonists.
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• Partial agonists have only moderate:
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intrinsic activity.
Hence their maximal efficacy is lower than that of full agonists. |
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• Partial agonists can act as agonists if
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there is no full agonist present
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Partial agonists can act as antagonists if:
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a full agonist is present.
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• Continuous exposure of cells to agonists can result in:
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receptor desensitization (aka refractoriness or down-regulation).
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continuous exposure of cells to antagonists can result in:
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hypersensitivity (aka supersensitivity).
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• The ED50 is defined as:
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the dose required to produce a defined therapeutic response in 50% of the population
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• An average effective dose (ED50) is perfect for some people, insufficient for others, and excessive for still others.:
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Because drug responses are not completely predictable, you must look at the patient (and not some drug reference book) to determine if dosage is appropriate.
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• The therapeutic index—defined as the LD50:ED50 ratio—is:
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a measure of a drug’s safety.
Drugs with a high therapeutic index are safe. Drugs with a low therapeutic index are not safe. |
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• Because of variability in responses, nurses, patients, and other concerned individuals must evaluate:
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actual responses and be prepared to inform the prescriber about these responses so that proper adjustments in dosage can be made.
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