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63 Cards in this Set

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List 4 reasons why a nurse needs a basic understanding of pharmacokinetics.
1. To teach(educate) pts.
2. Make PRN decisions.
3. Evaluate pts. for drug responses, both beneficial and harmful.
4. Conferring with physicians.
What is maximal efficacy?
the max. effect a drug can produce.
Why is it not necessarily desirable to use the drug with maximal efficacy?
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.
What is potency?
A potent drug is one that produces its effects at low doses.
Explain the difference bw what is meant by potency of a drug and maximal efficacy.
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.
What is a drug receptor?
Any functional macromolecule in a cell to which a drug binds to produce its effects.
What are 5 macromolecules, receptors or target molecules, where drugs may bind to cause a response?
1.Hormones
2.Neurotransmitters
3. Regulatory molecules
4. Enzymes
5.Ribosomes
Define endogenous.
Produced or originating from within a cell or organisms.
Explain the concept of selectivity.
A drug being able to interact w/ several different receptor types has a high selectivity.
How does selectivity relate to potential side effects of drugs?
The higher the selectivity, the less of a potential for side effects.
What are the two basic principles of the simple occupancy theory of drug-receptor interaction?
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.
What is affinity?

(Modified Occupancy Theory)
refers to the strength of the attraction bw a drug and its receptor.
What is intrinsic activity?

(Modified Occupancy Theory)
the abiliy of a drug to activate the receptor following binding.
What can be said regarding the potency of a drug that has a high affinity for a receptor?
would be very potent.
What can be said regarding the efficacy of a drug that has high intrinsic activity?
have a high maximal efficacy.
What is an agonist?
Molecules that activate receptors or drugs that mimic the body's own regulatory molecules.
What is an antagonist?
produces its effects by preventing receptor activation by endogenous regulatory molecules and drgus. Has virtually no effects of own on receptor function.
What is a partial agonist?
Has only moderate intrinsic activity.
Describe an agonist in terms of affinity and intrinsic activity.
Has both affinity and high intrinsic activity.
Describe an antagonist in terms of affinity and intrinsic activity.
Has affinity for a receptor but with no intrinsic activity.
Explain how a partial agonist can act as an antagonist as well as an agonist.
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.
What is another way drugs may cause an action if they do not bind to receptors?
Some drugs act thru simple physical or chemical interactions w/ other small molecules rather than thru receptors.
What is ED50?
the average effective dose.
What is LD50?
the average lethal does. The dose that is lethal to 50%
of the animals treated.
What is therapeutic index?
A measure of a drug's safety. The ratio of a drug's LD50 to it's ED50.
What can be said regarding the therapeutic index of a drug w/ a narrow therapeutic range?
A drug w/ a narrow therapeutic range would have a low therapeutic index.
What can be said regarding the therapeutic index of a drug with a wide therapeutic range?
A drug w/ a wide therapuetic range would have a high therapeutic index.
True or False?

All drug-drug interactions are undesirable.
False
True or False?

All drug-drug interactions are unintended.
False
True or False?

All drug-drug interactions are predictable and therefore avoidable.
False.
List the three possible outcomes when 2 drugs interact.
1. Intensification of drugs
2. Increased therapeutic effects.
3. Increased adverse effects.
What is potentiative?
when a pt. is taking 2 meds, 1 drug may intensify the effects of the other.
Explain the benefits or detriments of potentiative interaction.
Anything that enhances therapeutic effects is beneficial. Any potentiative interaction that intensifies adverse effects is detrimental.
How is the interaction of sulbactum and ampicillin beneficial?
When admin alone, ampicillin undergoes rapid inactivation by bacterial enzymes. Sulbactum inhibits those enzymes, and thereby prolongs and intensifies ampicillin's therapeutic effects.
How is the interaction of aspirin and warfarin detrimental?
Aspirin can increase the pt's risk for bleeding bc it can increase the response to warfarin.
Define inhibitory.
Interactions that result in reduced drug effects.
Explain the benefits or detriments of inhibitory interactions.
Inhibitory interactions that reduce toxicity are beneficial. Inhibitory interactions that reduce therapeutic effects are detrimental.
How is the interaction of albuterol and propranolol detrimental?
When taken together, propranolol can reduce albuterol's therapeutic effects , so it would be unable to dilate the bronchi.
How is the interaction of morphine and naloxone beneficial?
Morphine can prod. coma and profound resp. depression and death can result. Naloxone can completely reverse all symptoms of toxicity.
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?
-a precipitate is formed
-drugs can be inactivated
How can antacids alter absorption?
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.
How can laxatives alter drug absorption?
can reduce absorption of other drugs by accelerating their passage through the intestine.
How can drugs that depress peristalsis alter drug absorption?
they prolong drug transit time in the intestine, thereby increasing the time for absorption.
How can drugs that induce vomiting alter drug absorption?
can decrease absorption of oral drugs.
How can adsorbent drugs alter drug absorption?
adsorbent drugs can adsorb other drugs onto themselves, thereby preventing absorption of the other drugs into the blood
How can drugs that reduce regional blood flow alter drug absorption?
can reduce absorption of other drugs from that region.
What are the 2 principle mechanisms by which 1 drug can alter the distribution of another?
-competition for protein binding
-alteration of extracellular pH
How do drugs increase the metabolism of other drugs?
by inducing synthesis of hepatic drug-metabolizing enzymes.
How might 1 drug alter renal excretion of another drug thru decreased glomerular filtration?
glomerular filtration can be decreased by drugs that reduce cardiac output.
What are the 2 basic types of pharmacodynamic drug interactions?
1. interactions in which the interacting drugs act at the SAME site
2.interactions in which the interacting drugs act at SEPARATE sites
What term may be used to almost always describe drug-drug interactions that occur at the same receptor site?
inhibitory
When does inhibition occur?
when an antagonist drug blocks access of an agonist drug to its receptor.
When can drug-drug interactions resulting from actions at separate sites be termed potentiative?
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.
What may be the result if 2 drugs that are both toxic to the same organ are given together?
they will cause more injury than if they were not combined.
ID 2 factors that increase the risk of drug-drug interactions.
1. the more drugs a pt receives
2. a low therapeutic index.
Name 5 ways drug-drug interactions may be minimized.
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
What effect does calcium containing food have on the absorption of tetracycline?
it causes them to bind and form an insoluble and nonabsorbable complex. absorption is reduced and antibacterial effects may be lost.
What effect do high fiber foods have on the absorption of digoxin?
reduces absorption. can result in therapeutic failure.
What is the citrus fruit that can inhibit the metabolism of certain drugs?
grapefruit
What food product can interact w/ theophylline and result in excessive CNS excitation?
caffeine
What electrolyte is present in salt substitutes that may interact w/ some diuretics?
potassium
What vitamin, involved in the clotting process, is found in common foods and may interact w/ a certain anticoagulant?
vitamin K can interact w/ warfarin
What is the recommended tiem fram to use when scheduling a drug to be administered "on an empty stomach" or "w/ meals?"
-with food means to administer w/ meal or shortly after
-on empty stomach means 1 hr before a meal or 2 hrs after.