Pharmacogenetics Worksheet

Review the PharmGKB website in the Online Resources tab for the course, including the following:
• https://www.pharmgkb.org/whatIsPharmgkb
• https://www.pharmgkb.org/page/searchingPharmgkb
• https://youtu.be/Yuja_6JRsFw?si=jjZA9dfF_J2VjF9B

Note: PharmGKB is for research purposes only and does not provide medical advice. It is, however, informative for your clinical decision making.
Case Study
An adult patient who recently had back surgery was prescribed codeine to control pain. They present at follow up with signs of a fungal infection in the surgical wound. They say that they are not getting adequate pain relief.

You want to prescribe the antifungal drug voriconazole and are considering switching to tramadol to better manage the patient’s pain.

1. What clinical guideline annotations, FDA drug label annotations, and level 1 clinical annotations (if any) are available for codeine?
2. What clinical guideline annotations, FDA drug label annotations, and level 1 clinical annotations (if any) are available for tramadol?
3. What clinical guideline annotations, FDA drug label annotations, and level 1 clinical annotations (if any) are available for voriconazole?

These are the patient’s genotypes at the relevant genes:

Gene Genotype
CYP2C19 2/2
CYP2D6 4/6

4. What is the patient’s CYP2C19 metabolizer status?
5. What is the patient’s CYP2D6 metabolizer status?
6. How might the patient’s metabolizer status explain their poor pain relief?
7. Would you have any concerns about replacing codeine with tramadol? Would you consider changes to the standard dosage?

Results from the fungal culture suggests that voriconazole is the best antifungal.

8. Would you have any concerns about prescribing voriconazole to this patient? Would you consider changes to the standard dosage?
9. Summarize for your patient in laypersons’ language the reasons for your clinical recommendations.