Chapter 03: Pharmacokinetics and Pharmacodynamics McCuistion: Pharmacology: A Patient-Centered Nursing Process Approach, 11th Edition

Which drug will go through a disintegration process after it is administered?

a. Intramuscular (IM) cephalosporins

b. Intravenous (IV) vasopressors

c. Oral analgesics

d. Subcutaneous insulin

ANS: C

When drugs are administered parenterally, there is no disintegration process, which occurs when a drug administered orally is broken down into smaller particles, eventually dissolving and becoming available for the body to absorb.

The nurse is preparing to administer an oral medication and wants to ensure a rapid drug action.

Which form of the medication will the nurse prefer to administer?

a. Capsule

b. Enteric-coated pill

c. Liquid suspension

d. Tablet

ANS: C

Liquid drugs are already in solution, which is the form necessary for absorption in the

gastrointestinal (GI) tract. The other forms must disintegrate into small particles and then

dissolve before being absorbed.

The nurse is teaching a patient who will be discharged home with a prescription for an enteric coated tablet. Which statement by the patient indicates understanding of the teaching?

a. "I may crush the tablet and put it in applesauce to improve absorption."

b. "I should consume acidic foods to enhance absorption of this medication."

c. "I should expect a delay in onset of the drug's effects after taking the tablet."

d. "I should take this medication with high-fat foods to improve its action."

ANS: C

Enteric-coated tablets resist disintegration in the acidic environment of the stomach and disintegrate when they reach the small intestine. There is usually some delay in onset of actions after taking these medications. Enteric-coated tablets should not be crushed or chewed, which would alter the time and location of absorption. Acidic foods will not enhance the absorption of the medication. The patient should not eat high-fat food before ingesting an enteric-coated tablet because high-fat foods decrease the absorption rate.

A patient who is newly diagnosed with type 1 diabetes mellitus asks why insulin must be given by subcutaneous injection instead of by mouth. The nurse will explain that this is because

a. absorption is diminished by the first-pass effects in the liver.

b. absorption is faster when insulin is given subcutaneously.

c. digestive enzymes in the GI tract break down the drug and prevent absorption.

d. the oral form is less predictable with more adverse effects.

ANS: C

Insulin, growth hormones, and other protein-based drugs are destroyed in the GI tract by digestive enzymes and must be given parenterally. Because insulin is destroyed by digestive

enzymes, it must be given parenterally and would not make it to the liver for metabolism with a first-pass effect.

The nurse is preparing to administer an oral medication that is water soluble. The nurse understands that this drug

a. must be taken on an empty stomach.

b. requires active transport for absorption.

c. should be taken with fatty foods.

d. will readily diffuse into the GI tract.

ANS: B

Water-soluble drugs require a carrier enzyme or protein to pass through the GI membrane for

absorption.

The nurse is preparing an injectable drug and wants to administer it via the route that will allow for the most rapid absorption possible. How will the nurse give this medication (if possible)?

a. IM into the deltoid muscle

b. IM into the gluteal muscle

c. SQ into abdominal tissue

d. SQ into the upper arm

ANS: A

Drugs given IM are absorbed faster in muscles that have the highest blood flow, such as the deltoid, rather than those with fewer blood vessels, such as the gluteals. Subcutaneous absorption is slower when compared to IM drug administration.

The nurse is reviewing medication information with a nursing student prior to administering an oral drug and notes that the drug has extensive first-pass effects. Which statement by the student indicates an understanding of the first-pass effect?

a. "The first-pass effect means the drug has 100% bioavailability."

b. "The first-pass effect means the drug is absorbed from the GI tract into the portal vein where it is transported to the liver and metabolized."

c. "The first-pass effect means the drug was given by injection and immediately metabolized."

d. "The first-pass effect means the drug may be unchanged as it passes through the liver."

ANS: B

Drugs that undergo first-pass metabolism are absorbed into the portal vein from the intestinal lumen and go through the liver, where they are metabolized to an inactive or a more active form.

The nurse prepares to change a patient's medication from an IV to an oral form and notes that the oral form is ordered in a higher dose. The nurse understands that this is due to differences in

a. bioavailability.

b. pinocytosis.

c. protein binding.

d. tachyphylaxis.

ANS: A

Oral drugs may have less bioavailability because a lower percentage of the drug reaches the systemic circulation. Pinocytosis refers to the process by which cells carry a solute across a membrane. Protein binding can occur with both routes. Tachyphylaxis describes a rapid decrease in response to drugs that occurs when tolerance develops quickly.

The nurse is preparing to administer a drug and learns that it is 90% protein bound. The patient's serum albumin level is low. The nurse will observe the patient for

a. decreased drug absorption.

b. decreased drug interactions.

c. decreased drug toxicity.

d. increased drug effects.

ANS: D

Drugs that are highly protein-bound bind with albumin and other proteins, leaving less free drug in circulation. If a patient has a low albumin, less drug is bound, and there is more free drug to cause drug effects. There would be a potential for increased interactions with other drugs and increased toxicity.

The nurse is administering two drugs to a patient and learns that both drugs are highly protein-bound. The nurse may expect

a. decreased bioavailability of both drugs.

b. decreased drug effects.

c. decreased drug interactions.

d. increased risk of adverse effects.

ANS: D

Two drugs that are highly protein-bound may compete for protein-binding sites, leaving more free drug in the circulation and an increased risk of adverse effects as well as increased drug effects, and an increased risk for drug interactions.

A patient has been taking a drug that is 75% protein bound. The provider adds a new medication that is 90% protein bound. The nurse will expect a potential

a. decreased drug effects of the first drug.

b. decreased therapeutic range of the first drug.

c. increased drug effects of the first drug.

d. increased therapeutic range of the first drug.

ANS: C

Adding another highly protein bound drug will potentially displace the first drug from protein binding sites and release more free drug, increasing the drug's effects. This does not alter the therapeutic range, which is the therapeutic serum level required for drug effectiveness before toxicity develops.

The nurse gives a highly metabolized medication to a patient with a history of liver disease. The nurse will monitor this patient for

a. decreased drug effects.

b. increased drug effects.

c. decreased therapeutic range.

d. increased therapeutic range.

ANS: B

Liver diseases such as cirrhosis and hepatitis alter drug metabolism due to the liver having a

lower capacity to metabolize medications. When the drug metabolism rate is decreased, excess

drug accumulation can occur and lead to toxicity.

The nurse gives 800 mg of a drug that has a half-life of 8 hours. How much drug will be left in the body in 24 hours if no additional drug is given?

a. None

b. 50 mg

c. 100 mg

d. 200 mg

ANS: C

Eight hours after the drug is given, there will be 400 mg left. Eight hours after that (16 hours), there will be 200 mg left. At 24 hours, there will be 100 mg left.

If a drug has a half-life of 12 hours and is given twice daily starting at 0800 on a Monday, when will a steady state be achieved?

a. 0800 on Tuesday

b. 0800 on Wednesday

c. 0800 on Thursday

d. 0800 on Friday

ANS: B

Steady-state levels occur after approximately 4 half-lives if the dose administered remains the same. Wednesday at 0800 is 4 half-lives from the original dose (12 hours × 4 = 48 hours).

The nurse is preparing to administer a drug that is ordered to be given twice daily. The nurse reviews the medication information and learns that the drug has a half-life of 24 hours. What will the nurse do next?

a. Administer the medication as ordered.

b. Contact the provider to discuss daily dosing.

c. Discuss every-other-day dosing with the provider.

d. Hold the medication.

ANS: B

A drug with a longer half-life should be given at longer intervals to avoid drug accumulation.

The nurse is caring for a patient who has ingested a large dose of aspirin several hours prior. It is determined that the patient has overdosed on aspirin. The provider orders sodium bicarbonate to be given. The nurse understands that this drug is given for which purpose?

a. To counter the toxic effects of the aspirin

b. To decrease the half-life of the aspirin

c. To increase the excretion of the aspirin

d. To neutralize the acid of the aspirin

ANS: C

Aspirin is a weak acid and is more readily excreted in alkaline urine. Sodium bicarbonate alkalizes the urine. It does not act as an antidote to aspirin, decrease the half-life, or neutralize its

pH.

The nurse is preparing to administer a drug that is eliminated through the kidneys. The nurse reviews the patient's chart and notes that the patient has increased serum creatinine and blood urea nitrogen (BUN) and a low estimated glomerular filtration rate (eGFR). The nurse will perform which action?

a. Administer the drug as ordered.

b. Anticipate a shorter than usual half-life of the drug.

c. Expect decreased drug effects when the drug is given.

d. Verify that the dose ordered is appropriate based on the patient's kidney function.

ANS: D

Increased creatinine and BUN and a low eGFR indicate impaired kidney function, so a drug that is eliminated through the kidneys can accumulate, leading to toxicity. The nurse should verify that the ordered dose is appropriate based on the patient's kidney function, and if not, discuss a lower dose or alternative medication with the provider. The drug will have a longer half-life and will exhibit increased effects with decreased kidney function.

The nurse understands that the length of time needed for a drug to reach the minimum effective concentration (MEC) is the

a. duration of action.

b. onset of action.

c. peak.

d. time response curve.

ANS: B

The onset of action is the time it takes to reach the MEC. Duration of action is the length of time a drug has a pharmacologic effect. A drug's peak occurs when the drug reaches its highest blood level. The time response curve is an evaluation of the other three measures.

The nurse administers albuterol to a patient who has asthma. The albuterol acts by stimulating beta2-adrenergic receptors to cause bronchodilation. The nurse understands that albuterol is a beta-adrenergic

a. agonist.

b. antagonist.

c. inhibitor.

d. depressant.

ANS: A

An agonist medication is one that stimulates a certain type of receptor to produce a therapeutic response.

The nurse is preparing to administer the first dose of digoxin (Lanoxin) to a patient and notes that the initial dose ordered is much higher than the ordered maintenance dose. Which of the following describes why the first dose is higher?

a. Digoxin requires a loading dose.

b. Digoxin undergoes first-pass metabolism when initially administered.

c. Digoxin has a long duration of action.

d. Digoxin has a short half-life.

ANS: A

The reason the first dose is higher than the ordered maintenance dose is because a loading dose is required. This is performed to more quickly reach steady state for a drug with a long half-life. The loading dose is not given due to first-pass metabolism or duration of action.

The nurse administers a centrally acting analgesic to a patient who has been receiving it for 1 day after orthopedic surgery with successful pain relief. The patient reports no change in pain 30 minutes after the medication is given. The nurse recognizes that this patient is likely exhibiting

a. drug-seeking behavior

b. drug tolerance.

c. the placebo effect.

d. tachyphylaxis.

ANS: D

Tachyphylaxis is a rapid decrease in response, or acute tolerance. Tolerance to drug effects can occur rapidly with centrally acting analgesics, requiring increased doses in order to achieve adequate drug effects. Nurses often mistake drug-seeking behavior for drug tolerance. The placebo effect occurs when the patient experiences a response with an inactive drug.

A patient has been taking a drug for several years and tells the nurse it is no longer working. The nurse learns that the patient has recently begun taking an over-the-counter (OTC) antacid medication. What does the nurse suspect is occurring?

a. An adverse drug reaction

b. A drug interaction

c. Drug incompatibility

d. Drug tolerance

ANS: B

Drug interactions are an altered or modified action or effect of a drug as a result of interaction with one or more other drugs. An adverse drug reaction can occur with one or more drugs. It is possible in this scenario that the antacid is preventing adequate absorption of the other medication. Drug incompatibility is a chemical reaction of two or more drugs that occurs in vitro. Drug tolerance is the development of reduced response to a medication over time.

The nurse is preparing to administer two IV medications that should not be given using the same IV tubing. The nurse understands that this is because of drug

a. adverse reactions.

b. incompatibility.

c. interactions.

d. potentiation.

ANS: B

Drugs that are incompatible cannot be mixed together in solution and cannot be mixed in a syringe, IV bag, or other artificial environment. Adverse reactions are symptoms occurring from drug effects. Drug interactions occur in vivo. Potentiation is when one drug causes an enhanced

response to another drug.

A patient who takes a drug that undergoes gastric absorption will begin taking an opioid analgesic after sustaining an injury in a motor vehicle accident. The nurse will observe the patient closely for which effects?

a. Decreased effects of the first drug

b. Increased effects of the first drug

c. Decreased effects of the narcotic

d. Increased effects of the narcotic

ANS: B

Opioids slow gastric emptying, allowing more time for drugs to be absorbed in the stomach. The nurse should expect a potential for increased effects of the first drug.

The nurse is teaching a patient who will begin taking ciprofloxacin (Cipro). What instruction will the nurse include when teaching this patient about this drug?

a. "Do not take this medication with oral contraceptive pills."

b. "Take at least 1 hour after or 2 hours before taking antacids."

c. "Take in the morning with your multivitamin tablet."

d. "Take with milk to reduce gastric upset."

ANS: B

Dairy products, multivitamins, and antacids should be avoided 1 hour after and 2 hours before taking ciprofloxacin because these products contain divalent cations that form a drug complex that prevents absorption of the ciprofloxacin.

The nurse is preparing to administer furosemide to a patient who takes digoxin. The nurse will plan to monitor the patient for

a. digoxin toxicity.

b. decreased digoxin effects.

c. furosemide toxicity.

d. decreased furosemide effects.

ANS: A

Increased loss of potassium through the kidneys can result in hypokalemia, which can enhance the action of digoxin and can lead to toxicity.

A patient is prescribed bethanechol (a cholinergic agent) to help manage her urinary retention. Which of the following would correctly describe a cholinergic response?

a. Pupillary constriction

b. Increased heart rate

c. Bronchiole relaxation

d. Increased blood pressure

ANS: A

Cholinergic medications like bethanechol can result in constriction of the pupils. Increased heart rate, increased blood pressure, and relaxation of the bronchioles would be associated with anticholinergic medication use.

A patient has been taking warfarin (Coumadin), which is highly protein-bound. The patient will begin taking gemfibrozil, which is also highly protein-bound. The nurse will observe the patient closely for

a. decreased effects of warfarin.

b. increased effects of warfarin.

c. decreased effects of gemfibrozil.

d. decreased effects of both drugs.

ANS: B

The addition of a highly protein-bound drug will compete with warfarin for protein-binding sites, releasing more free warfarin into the system, increasing drug effects, and increasing the chance of toxicity (bleeding).

A patient is taking phenytoin to prevent seizures. The nurse knows that phenytoin is highly protein-bound and has sedating effects. The nurse reviews the patient's chart and notes a low serum albumin. The nurse will notify the provider and observe the patient for which effects?

a. Decreased sedative effects

b. Increased sedative effects

c. Increased seizures

d. No change in effects

ANS: B

Phenytoin is highly protein-bound. When patients have a low serum albumin, there are fewer protein-binding sites, resulting in more free drug in the system. The nurse should expect the

potential for an increase in the sedative side effects of phenytoin.

A patient who takes the anticoagulant warfarin will begin taking the anticonvulsant drug carbamazepine. The nurse reviews the drug information for these drugs and learns that carbamazepine is a hepatic enzyme inducer. The nurse anticipates that which of the following may be required?

a. Decrease the dose of carbamazepine.

b. Increase the dose of carbamazepine.

c. Decrease the dose of warfarin.

d. Increase the dose of warfarin.

ANS: D

Carbamazepine is a hepatic enzyme inducer, which can increase drug metabolism. Patients taking both drugs usually need a larger dose of warfarin. Warfarin therapeutic drug monitoring would be indicated to assess the impact of the carbamazepine on his warfarin effectiveness.

The nurse is caring for a patient who receives theophylline, which has a narrow therapeutic index. The patient has been receiving cimetidine but will stop taking that drug in 2 days. In 2 days, the nurse will observe the patient closely for

a. decreased effectiveness of theophylline.

b. increased effectiveness of theophylline.

c. decreased toxicity of theophylline.

d. prolonged effectiveness of theophylline.

ANS: B

Cimetidine is an enzyme inhibitor that decreases the metabolism of drugs such as theophylline. If the cimetidine is discontinued, the theophylline dose should be decreased to avoid toxicity. The nurse should observe the patient for increased theophylline effects.

A patient will receive penicillin to treat an infection. The provider orders probenecid (Probalan), a medication to treat gout, even though the patient does not have gout. Which action by the nurse

is correct?

a. Administer the drug since the provider ordered it.

b. Recognize that it is being given prophylactically.

c. Refuse to administer the medication since it is not indicated.

d. Verify that it is being given for its secondary action.

ANS: D

Two or more drugs with the same route of excretion may compete with each other for elimination. Probenecid is given because it inhibits the excretion of penicillin, which may be

desirable when the provider wants to increase the plasma concentration of penicillin. The nurse should always verify an order that may not be clear.

The provider has ordered amoxicillin with clavulanate (Augmentin) for a child who has otitis media. The child's parent asks why this drug is necessary when amoxicillin is less expensive. The nurse will explain that clavulanate is added to amoxicillin because it

a. binds with albumin to increase the amount of available amoxicillin.

b. enhances the antibacterial effect of amoxicillin by inhibiting bacterial enzymes.

c. inhibits hepatic blood flow, leading to increased serum drug levels of amoxicillin.

d. inhibits the excretion of amoxicillin by interfering with renal function.

ANS: B

Clavulanate is a bacterial enzyme inhibitor, specifically beta-lactamase, which inactivates amoxicillin. When added to amoxicillin, it enhances the antibacterial effect.

The nurse assesses a patient who is receiving morphine sulfate intravenously using a patient controlled analgesia pump. The nurse notes somnolence and respiratory depression, which are signs of morphine toxicity. The nurse will prepare to administer naloxone (Narcan) because it

a. has synergistic effects with morphine.

b. is an opioid agonist.

c. is an opioid antagonist.

d. potentiates the effects of morphine.

ANS: C

Naloxone is an opioid antagonist, meaning that it reverses the effects of morphine by blocking

morphine receptor sites.

The nurse is teaching a patient about a drug that causes photosensitivity. Which statement by the patient indicates a need for further teaching?

a. "I should apply sunscreen with a sun protection factor greater than 15."

b. "I should avoid sunlight when possible while taking this drug."

c. "I will wear protective clothing when I am outdoors."

d. "I will wear sunglasses even while I am indoors."

ANS: D

Drugs that cause photosensitivity make sunburn more likely, so patients should stay out of the

sun, wear protective clothing, and use sunscreen with an SPF greater than 15. It is not necessary

to wear sunglasses indoors.

A patient asks the nurse about using OTC medications. The nurse will tell the patient that OTC medications

a. are not as effective as prescription medications.

b. are not as safe as prescription medications.

c. have fewer side effects and drug interactions than prescription medications.

d. should be included when listing any medications taken by the patient.

ANS: D

OTC medications should always be included when listing medications because they can

contribute to drug interactions. OTC medications can be as effective and as safe as prescription

medications and can have as many side effects and adverse reactions as prescription medications.

A patient calls the clinic and tells the nurse that a newly prescribed medication isn't working. What is the nurse's next action?

a. Notify the provider and discuss increasing the dose.

b. Question the patient about compliance with the regimen.

c. Review the drug information with the patient.

d. Suggest the patient discuss changing medications with the provider.

ANS: C

It is important for patients to understand the therapeutic effects and expected time frame for effects to occur. The nurse should review this with the patient first to make sure the patient's expectations are consistent with the drug's effects. The dose should not be increased or the drug changed until it is determined that the drug is not working as it should. Questioning the patient about compliance first assumes that the patient is doing something wrong. The nurse may question the patient about compliance after reviewing the drug information.

The community health nurse is teaching a group of elderly residents in an assisted care facility about medication use. The nurse will remind the residents that OTC medications

a. are not as effective as prescription medications.

b. are not recommended for older adults.

c. are safer than prescription medications.

d. should be reviewed with a provider before taking.

ANS: D

OTC medications should be reviewed as part of a medication history at every encounter with the provider to prevent food and drug interactions. OTC medications may be just as effective as prescription medications, may be used by older adults, and can have serious side effects.

The nurse is preparing to teach a patient who will begin taking a non-selective monoamine oxidase (MAO) inhibitor. What is most important when teaching patients about non-selective MAO inhibitors?

a. Emphasizing the importance of potassium intake

b. Giving detailed drug information

c. Reviewing dietary guidelines

d. Providing a schedule for medication administration

ANS: C

Non-selective MAO inhibitors have many dietary restrictions with potentially serious adverse reactions, so this should be an important part of teaching.

The nurse is teaching a patient about taking a once-daily medication that has a side effect of drowsiness. The nurse learns that the patient works a 7:00 PM to 7:00 AM shift in a hospital. The nurse will recommend that the patient take this medication at which time of day?

a. 0600

b. 0800

c. 1800

d. 2000

ANS: B

The medication should be given when the patient is at home before sleep.

Which patients are at particularly high risk for drug interactions? (Select all that apply.)

a. Patients who are acutely ill

b. Patients who are taking multiple medications

c. Patients who see several specialists

d. Patients who take supplements and OTC medications

e. Patients who use one pharmacy for several medications

ANS: B, C, D

Patients who have chronic health conditions, take multiple medications, see more than one provider, and use supplements and OTC medications are at higher risk for drug interactions.