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63 Cards in this Set
- Front
- Back
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List 4 reasons why a nurse needs a basic understanding of pharmacokinetics.
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1. To teach(educate) pts.
2. Make PRN decisions. 3. Evaluate pts. for drug responses, both beneficial and harmful. 4. Conferring with physicians. |
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What is maximal efficacy?
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the max. effect a drug can produce.
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Why is it not necessarily desirable to use the drug with maximal efficacy?
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We want to match intensity of the response to the pts. needs. This may be difficult to do with a drug tat produces extremely intense responses. ex: Wouldn't want to prescribe morphine for a headache.
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What is potency?
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A potent drug is one that produces its effects at low doses.
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Explain the difference bw what is meant by potency of a drug and maximal efficacy.
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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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What is a drug receptor?
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Any functional macromolecule in a cell to which a drug binds to produce its effects.
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What are 5 macromolecules, receptors or target molecules, where drugs may bind to cause a response?
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1.Hormones
2.Neurotransmitters 3. Regulatory molecules 4. Enzymes 5.Ribosomes |
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Define endogenous.
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Produced or originating from within a cell or organisms.
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Explain the concept of selectivity.
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A drug being able to interact w/ several different receptor types has a high selectivity.
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How does selectivity relate to potential side effects of drugs?
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The higher the selectivity, the less of a potential for side effects.
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What are the two basic principles of the simple occupancy theory of drug-receptor interaction?
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1. The intensity of the response to a drug is proportional to the # of receptors occupied by that drug.
2. A maximal response will occur when ALL available receptors have been occupied. |
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What is affinity?
(Modified Occupancy Theory) |
refers to the strength of the attraction bw a drug and its receptor.
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What is intrinsic activity?
(Modified Occupancy Theory) |
the abiliy of a drug to activate the receptor following binding.
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What can be said regarding the potency of a drug that has a high affinity for a receptor?
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would be very potent.
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What can be said regarding the efficacy of a drug that has high intrinsic activity?
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have a high maximal efficacy.
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What is an agonist?
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Molecules that activate receptors or drugs that mimic the body's own regulatory molecules.
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What is an antagonist?
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produces its effects by preventing receptor activation by endogenous regulatory molecules and drgus. Has virtually no effects of own on receptor function.
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What is a partial agonist?
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Has only moderate intrinsic activity.
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Describe an agonist in terms of affinity and intrinsic activity.
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Has both affinity and high intrinsic activity.
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Describe an antagonist in terms of affinity and intrinsic activity.
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Has affinity for a receptor but with no intrinsic activity.
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Explain how a partial agonist can act as an antagonist as well as an agonist.
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It can bind to a receptor and activate it or if another drug is admin, it could also prevent the activation of that drug's receptors.
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What is another way drugs may cause an action if they do not bind to receptors?
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Some drugs act thru simple physical or chemical interactions w/ other small molecules rather than thru receptors.
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What is ED50?
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the average effective dose.
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What is LD50?
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the average lethal does. The dose that is lethal to 50%
of the animals treated. |
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What is therapeutic index?
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A measure of a drug's safety. The ratio of a drug's LD50 to it's ED50.
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What can be said regarding the therapeutic index of a drug w/ a narrow therapeutic range?
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A drug w/ a narrow therapeutic range would have a low therapeutic index.
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What can be said regarding the therapeutic index of a drug with a wide therapeutic range?
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A drug w/ a wide therapuetic range would have a high therapeutic index.
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True or False?
All drug-drug interactions are undesirable. |
False
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True or False?
All drug-drug interactions are unintended. |
False
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True or False?
All drug-drug interactions are predictable and therefore avoidable. |
False.
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List the three possible outcomes when 2 drugs interact.
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1. Intensification of drugs
2. Increased therapeutic effects. 3. Increased adverse effects. |
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What is potentiative?
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when a pt. is taking 2 meds, 1 drug may intensify the effects of the other.
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Explain the benefits or detriments of potentiative interaction.
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Anything that enhances therapeutic effects is beneficial. Any potentiative interaction that intensifies adverse effects is detrimental.
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How is the interaction of sulbactum and ampicillin beneficial?
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When admin alone, ampicillin undergoes rapid inactivation by bacterial enzymes. Sulbactum inhibits those enzymes, and thereby prolongs and intensifies ampicillin's therapeutic effects.
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How is the interaction of aspirin and warfarin detrimental?
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Aspirin can increase the pt's risk for bleeding bc it can increase the response to warfarin.
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Define inhibitory.
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Interactions that result in reduced drug effects.
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Explain the benefits or detriments of inhibitory interactions.
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Inhibitory interactions that reduce toxicity are beneficial. Inhibitory interactions that reduce therapeutic effects are detrimental.
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How is the interaction of albuterol and propranolol detrimental?
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When taken together, propranolol can reduce albuterol's therapeutic effects , so it would be unable to dilate the bronchi.
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How is the interaction of morphine and naloxone beneficial?
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Morphine can prod. coma and profound resp. depression and death can result. Naloxone can completely reverse all symptoms of toxicity.
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What are 2 undesirable effects that can take place when drugs that have incompatible physical or chemical props are mixed in the same IV bottle or IV tubing?
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-a precipitate is formed
-drugs can be inactivated |
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How can antacids alter absorption?
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can decrease ionization of basic drugs in stomach, which increases the ability of basic drugs to cross mem and be absorbed. Has opposited effect on acidic drugs.
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How can laxatives alter drug absorption?
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can reduce absorption of other drugs by accelerating their passage through the intestine.
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How can drugs that depress peristalsis alter drug absorption?
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they prolong drug transit time in the intestine, thereby increasing the time for absorption.
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How can drugs that induce vomiting alter drug absorption?
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can decrease absorption of oral drugs.
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How can adsorbent drugs alter drug absorption?
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adsorbent drugs can adsorb other drugs onto themselves, thereby preventing absorption of the other drugs into the blood
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How can drugs that reduce regional blood flow alter drug absorption?
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can reduce absorption of other drugs from that region.
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What are the 2 principle mechanisms by which 1 drug can alter the distribution of another?
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-competition for protein binding
-alteration of extracellular pH |
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How do drugs increase the metabolism of other drugs?
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by inducing synthesis of hepatic drug-metabolizing enzymes.
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How might 1 drug alter renal excretion of another drug thru decreased glomerular filtration?
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glomerular filtration can be decreased by drugs that reduce cardiac output.
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What are the 2 basic types of pharmacodynamic drug interactions?
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1. interactions in which the interacting drugs act at the SAME site
2.interactions in which the interacting drugs act at SEPARATE sites |
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What term may be used to almost always describe drug-drug interactions that occur at the same receptor site?
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inhibitory
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When does inhibition occur?
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when an antagonist drug blocks access of an agonist drug to its receptor.
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When can drug-drug interactions resulting from actions at separate sites be termed potentiative?
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if both drugs influence the same physiologic process,then 1 drug can alter responses prod. by the other. Sometimes this can be potentiative or it can be inhibitory.
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What may be the result if 2 drugs that are both toxic to the same organ are given together?
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they will cause more injury than if they were not combined.
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ID 2 factors that increase the risk of drug-drug interactions.
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1. the more drugs a pt receives
2. a low therapeutic index. |
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Name 5 ways drug-drug interactions may be minimized.
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1. min the # of drugs a pt receives
2. take a thorough drug history 3. adjust dosage when a metabolism inducer is added or deleted from reimen 4.adjusting timing of admin to min interference w/ absorption 5.monitoring for toxicity when combos of toxic agents can't be avoided |
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What effect does calcium containing food have on the absorption of tetracycline?
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it causes them to bind and form an insoluble and nonabsorbable complex. absorption is reduced and antibacterial effects may be lost.
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What effect do high fiber foods have on the absorption of digoxin?
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reduces absorption. can result in therapeutic failure.
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What is the citrus fruit that can inhibit the metabolism of certain drugs?
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grapefruit
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What food product can interact w/ theophylline and result in excessive CNS excitation?
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caffeine
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What electrolyte is present in salt substitutes that may interact w/ some diuretics?
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potassium
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What vitamin, involved in the clotting process, is found in common foods and may interact w/ a certain anticoagulant?
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vitamin K can interact w/ warfarin
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What is the recommended tiem fram to use when scheduling a drug to be administered "on an empty stomach" or "w/ meals?"
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-with food means to administer w/ meal or shortly after
-on empty stomach means 1 hr before a meal or 2 hrs after. |
