Question 1

You are aware of a research study being conducted in your organization where genetic testing is being completed on each client before medications are prescribed. What should you expect the results of this testing to accomplish?

Accepted Answer

One benefit of pharmacogenomics is a more accurate method of determining drug dosages. Pharmacogenomics is not used to identify multiple uses for the same medication, reduce the cost to manufacture medications, or reduce the use of medications to treat health problems.

Question 2

Through genetic testing, a client learns of having a natural variation in a chromosome and gene. How should this finding affect the client's metabolism of medications?

Accepted Answer

The client has a polymorphism, which is a natural variation in a gene, DNA
sequence, or chromosome that has no adverse effects on the person but will cause differences in drug response because of the genes encoding drug-metabolizing enzymes, drug transporters, or drug targets. The polymorphism will affect drug metabolism. There is no way to predict that medications will be metabolized as intended or the number of medications that the client can metabolize is limited.

Question 3

A client with the CYP gene is identified as being a poor metabolizer. What dose should you expect when a cardiovascular drug is prescribed for this client?

Accepted Answer

The CYP enzymes include approximately 57 liver enzymes that metabolize
more than 30 classes of drugs, including antidepressants, antiepileptics, and cardiovascular drugs. Based on variations in the associated CYP gene, clients can be separated into poor, normal, and ultrarapid drug metabolizers. When a client who is a poor metabolizer of a particular drug is given a standard dose, the drug will be processed more slowly than expected, resulting in increased levels of the drug in the person's bloodstream. This can increase the risk for side effects and toxicity. The usual dose may cause side effects and toxicity. A higher than normal dose or a dose that is three times the normal dose will definitely cause side effects and toxicity.

Question 4

A client taking isoniazid as part of treatment for tuberculosis is not demonstrating any improvement in the infection. What should you suspect is occurring with this client?

Accepted Answer

N-acetyltransferase is a liver enzyme that activates some drugs and
deactivates others. A client who is a fast accelerator of this enzyme may not respond to isoniazid. The TPMT enzyme is used to metabolize azathioprine and other thiopurine medications. The CYP gene plays a role in the metabolism of antidepressants, antiepileptics, and cardiovascular drugs. UDP-glucuronosyltransferase is involved in the metabolism of irinotecan.

Question 5

A client is prescribed a thiopurine medication to treat inflammatory bowel disease. Which laboratory value should indicate to you that the client has sufficient TPMT to metabolize this medication?

Accepted Answer

A client who has low or limited amounts of TPMT to metabolize a thiopurine medication will demonstrate severe hematopoietic toxicity which affects red blood cell and platelet levels. The client with sufficient TPMP will not demonstrate hematopoietic toxicity and will have a normal red blood cell count.

Question 6

A client is receiving irinotecan as treatment for metastatic colorectal cancer. Which symptom should indicate to you that the client has a UDP- glucuronosyltransferase deficiency?

Accepted Answer

UDP-glucuronosyltransferase is involved in the metabolism of irinotecan,
a chemotherapeutic drug that is used in the treatment of metastatic colorectal cancer. Variations in the gene that codes for this enzyme can influence the client's ability to break down the major active metabolite in irinotecan. The inability to degrade the metabolite can lead to increased blood concentrations and increased risk of experiencing severe diarrhea. Muscle cramps, rapid respirations, and low blood pressure are not symptoms that indicate a deficiency of UDP-glucuronosyltransferase.

Question 7

A client needs to be prescribed warfarin. Which gene helps determine the dose and effectiveness of this medication?

Accepted Answer

The CYP2C9 genotype has been shown to incrementally improve prediction of warfarin dose maintenance. More than 30 medications are metabolized by CYP2D6, including analgesics, antidepressants, and antiemetics. The UGT1A1 gene produces the enzyme UDP-glucuronosyltransferase. CYP2C19 is not identified as impacting the metabolism of warfarin.

Question 8

A client is deficient in the CYUP2D6 enzyme. Which medication classification should you question before giving to this client?

Accepted Answer

More than 30 medications are metabolized by the CYUP2D6 enzyme, including analgesics, antidepressants, and antiemetics. Antibiotics, antiepileptics, and antihypertensives are not medications that need the enzyme CYUP2D6 for metabolism.

Question 9

A client is found to have an increased level of the VKORC1 enzyme. How should you expect the client's dose of warfarin to be affected?

Accepted Answer

Warfarin acts by inhibiting vitamin K epoxide reductase complex subunit
1 (VKORC1). If the client has a higher level of the VKORC1 enzyme, the amount of warfarin dose should be increased to overcome the resistance to vitamin K. If the warfarin dose is unchanged or lower, it will take longer for effective anticoagulation to occur. There is no need to identify a different anticoagulant; the dose just needs to be adjusted upward.

Question 10

A pharmaceutical company is implementing a drug program that is based upon extensive genomic testing conducted on one ethnic group. How will this affect some of your clients?

Accepted Answer

The future of pharmacogenomics will most likely focus on the development of drugs that work well with certain population groups; however, any program will need to
be carefully implemented to avoid a perception of stigma based on ethnicity. Assuming that an individual's race can be used as a genetic profile can be a potential problem. There is no evidence that all clients within the ethnic group will have better outcomes. Individually targeted drug therapy is very attractive and is likely to be very expensive, regardless of testing on a specific ethnic group.

Quiz 25: Pharmacogenomics