Nursing

Week 12 # 2

The following results are from an actual patient who underwent testing using a commercial vendor (CompanionDx).  The genotype information contained in the report is part of the patient's medical record. Given this information, you should provide your answers to the following questions on this week's Discussion Board. Please note that some of these questions are not (necessarily) right/wrong questions, but merely raise issues that should foster discussion.

The patient has been diagnosed with atrial fibrillation and is at an increased risk of thromboembolism. He is otherwise healthy, has normal liver/renal function and is on no other medications.  You have decided to place him on anti-coagulation therapy using Coumadin (warfarin). 

Please discuss the following questions based on his genetic testing data. 

CYP2C9genotype: *2/*3V

VKORC1 genotype: AA

FDA label: http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/009218s107lbl.pdf 

1-1  Based on the FDA's guidance on prescribing this medication to individuals with CYP2C9 and VKORC1 polymorphisms, what would you predict will be his stable warfarin dose? How might he respond to a 6 mg dose of warfarin? 

1-2  What are the ramifications if you elect NOT to use his PGx information in your treatment decision given that it is in his medical record?   

2. You review his CYP2D6 genotypic information: CYP2D6genotype: *4/*4.  Based on this information, how would you predict he will respond to the following drugs?  Please cite evidence from the primary scientific literature (i.e. PubMed) to support your conclusion.  You may use the resources listed at the end of this week’s lecture.            

a) Tamoxifen            b) Codeine c) Paroxetine: would your answer have been different for this drug if he were CYP2D6*2/*2xN (Ultra-rapid metabolizer)?