Question 1

A patient asks a nurse why a friend who is taking the same drug responds differently to that drug. The nurse knows that the most common variation in drug response is due to differences in each patient's:

A) drug receptor sites.
B) hypersensitivity potential.
C) metabolism of drugs.
D) psychosocial response.

metabolism of drugs.

Accepted Answer

The most common source of genetic variation in drug response is related to alterations in drug metabolism and is determined by genetic codes for various drug-metabolizing isozymes. There are known genetic differences in codes for drug target sites, but these are not as numerous as those for metabolic isozymes. Hypersensitivity potential is also genetically determined, but variations produce differences in adverse reactions to drugs and not in drug effectiveness. Psychosocial responses vary for many, less measurable reasons, such as individual personalities and variations in cultures.

Question 2

A nurse is preparing to care for a patient who is receiving digoxin. To help minimize the potential for adverse effects from this drug, the nurse will review which of this patient's laboratory results?

A) Albumin
B) Blood urea nitrogen (BUN) and creatinine
C) Hepatic enzymes
D) Serum electrolytes

Serum electrolytes

Accepted Answer

Patients with low serum potassium are at risk for fatal cardiac dysrhythmias when taking digoxin, and it is essential to know this level before this medication is administered. Knowing a patient's albumin level would be important when giving drugs that are protein bound. The BUN and creatinine levels are indicators of renal function. Hepatic enzymes are important to know when drugs are metabolized by the liver.

Question 3

The U.S. Food and Drug Administration (FDA) recommends genetic testing of patients receiving certain medications. Genetic testing helps prescribers:&#10;A) better establish a drug's therapeutic index.&#10;B) determine whether a patient is a rapid or slow metabolizer of the drug.&#10;C) identify racial characteristics that affect psychosocial variation in drug response.&#10;D) produce a drug that is tailored to an individual patient's genetic makeup.

Accepted Answer

Pharmacogenomics is the study of the ways genetic variations affect individual responses to drugs through alterations in genes that code for drug-metabolizing enzymes and drug receptors. For some drugs, the FDA requires genetic testing and for others, this testing is recommended but not required. Genetic testing does not determine a drug's therapeutic index; this is a measure of a drug's safety based on statistics of the drug's use in the general population (see Chapter 5). Any distinct physiological differences in drug response among various racial populations are related to genetic differences and do not affect psychosocial differences in drug responses. Genetic testing is recommended to identify how a patient will respond to a drug and not to design a drug specific to an individual.

Question 4

A patient has been taking narcotic analgesics for chronic pain for several months. The nurse caring for this patient notes that the prescribed dose is higher than the recommended dose. The patient has normal vital signs, is awake and alert, and reports mild pain. What does the nurse recognize about this patient?

A) This patient exhibits a negative placebo effect with a reduced response to the drug.
B) This patient has developed a reaction known as tachyphylaxis because of repeated exposure to the drug.
C) This patient has developed pharmacodynamic tolerance, which has increased the minimal effective concentration (MEC) needed for analgesic effect.
D) This patient produces higher than normal hepatic enzymes as a result of prolonged exposure to the drug.

Accepted Answer

Pharmacodynamic tolerance results when a patient takes a drug over a period of time. Adaptive processes occur in response to chronic receptor occupation. The result is that the body requires increased drug, or an increased MEC, to achieve the same effect. This patient is getting adequate pain relief, so there is no negative placebo effect. Tachyphylaxis is a form of tolerance that can be defined as a reduction in drug responsiveness brought on by repeated dosing over a short time; this occurs over several months. Barbiturates induce synthesis of hepatic enzymes that cause increased metabolism of the drug, but it does not increase the MEC.

Question 5

A nurse is caring for a woman with breast cancer who is receiving tamoxifen. A review of this patient's chart reveals a deficiency of the CYP2D6 gene. The nurse will contact the provider to suggest:&#10;A) a different medication.&#10;B) an increased dose.&#10;C) a reduced dose.&#10;D) serum drug levels.

Accepted Answer

Women with a deficiency of the CYP2D6 gene lack the ability to convert tamoxifen to its active form, endoxifen, and will not benefit from this drug. Another drug should be used to treat this patient's breast cancer. Increasing the dose, reducing the dose, or monitoring serum drug levels will not make this drug more effective in these women.

Question 6

A nurse is teaching a group of women about medications. The women want to know why so many drugs have unpredictable effects in women. The nurse will tell them that:&#10;A) drugs usually have more toxic effects in women.&#10;B) most known drug effects are based on drug trials in men.&#10;C) women have varying responses to drugs during menstrual cycles.&#10;D) women metabolize drugs more slowly.

Accepted Answer

Until 1997 almost all clinical drug trials were performed in men. Women may have more toxic effects with some drugs and fewer toxic effects with others. Not all drugs are influenced by hormonal changes. Women metabolize some drugs more slowly and other drugs more quickly. Unless drug trials are performed in both women and men, the effects of drugs in women will not be clear.

Question 7

A nurse administers the same medication in the same preparation in the same dose to several patients and notes that some patients have a better response to the drug than others. What is the most likely explanation for this phenomenon?

A) Altered bioavailability of the drug
B) Patient compliance with the therapeutic regimen
C) Pharmacogenomic differences among individuals
D) Placebo effects enhancing expectations of drug efficacy

Accepted Answer

Each patient's genetic makeup can determine how that patient responds to drugs both quantitatively and qualitatively, and this is the most likely cause of individual variation when the same drug is given at the same dose. The bioavailability of a drug is determined by the drug's composition and varies across formulations of the drug. The patients in this example were given the same drug. The nurse was administering the medication to the patients, so compliance is not an issue. Nothing in this example indicates that a placebo effect was in play.

Question 8

Which groups of people are especially sensitive to medication effects? (Select all that apply.)&#10;A) Older adults&#10;B) Caucasians&#10;C) Infants&#10;D) Minorities&#10;E) Women

Accepted Answer

Older adults and infants are the two groups most sensitive to drugs because of differences in organs that absorb, metabolize, and excrete drugs. In the older adult, organ degeneration accounts for these differences, whereas in infants the differences are related to organ immaturity. Racial and gender differences tend to be related to genetic differences and not race and gender per se. These groups are more sensitive to drug effects in some cases and less sensitive in other cases.

Question 9

A postoperative patient who is worried about pain control will be discharged several days after surgery. The nurse providing discharge teaching tells the patient that the prescribed Lortab is not as strong as the morphine the patient was given in the immediate postoperative period. Which response is the patient likely to experience?

A) A decreased likelihood of filling the prescription for the drug
B) A negative placebo effect when taking the medication
C) An increased compliance with the drug regimen
D) Optimistic, realistic expectations about the drug

Accepted Answer

The full extent of placebo effects, if they truly occur, is not well documented or understood, although a decrease in pain as a placebo effect has been demonstrated to some extent. To foster a beneficial placebo effect, it is important for all members of the healthcare team to present an optimistic and realistic assessment of the effects of the drug the patient is taking. If the nurse tells an anxious patient that the medication being given is not as strong as what has been given, the patient is likely to have lowered expectations of the effectiveness of the drug, causing a negative placebo effect. Lowered expectations do not mean that the patient will give up on the drug entirely; in fact, the patient may actually fill the prescription and then take more drug than what is prescribed in order to get a better effect.

Deck 8: Individual Variation in Drug Responses