Final answer:
An INR of 4.5 is elevated and may require a dose adjustment and possibly vitamin K administration, depending on the individual's risk of bleeding. Pharmacogenomics can assist by tailoring warfarin dosing to the patient's genetic profile.
Step-by-step explanation:
The subject of the question pertains to the management of a patient with a high international normalized ratio (INR) who is likely on warfarin therapy, which is used to prevent thrombotic events. In this scenario, an INR of 4.5 is considered elevated, as the typical therapeutic range is between 2.0 and 3.0 for most indications. In this case, the nurse practitioner should assess the patient's risk of bleeding, check for potential interactions with other medications, and consider the patient's recent dietary changes, as vitamin K intake can affect INR levels. The appropriate action would often involve holding a dose of warfarin and possibly administering oral vitamin K, especially if there is a significant risk of bleeding or the patient is showing signs of bleeding. However, if the INR is significantly elevated without bleeding, a reduction in the dose of warfarin and close monitoring may be sufficient.
Regarding the use of pharmacogenomics, it can be employed to tailor drug dosing to the individual needs of the patient. Warfarin dosing can be variable among patients due to differences in genes that affect drug metabolism and sensitivity. Pharmacogenetic testing of the liver enzymes that metabolize warfarin, like CYP2C9 and VKORC1, can help predict the patient's response to warfarin and guide dosing to reduce the risk of overdose or underdose.