Patient discussions
Patients benefit from education surrounding both their disease as well as therapy. In particular, anticoagulants confer a risk for bleeding, and educating patients on the signs and symptoms of bleeding, avoiding concomitant drugs that increase bleeding risk (such as Nonsteroidal anti-inflammatory drugs [NSAIDs]), and being judicious in choice of activities with risk for injury are perceived by patients to be beneficial.[318][319] As with all medical therapy, emphasizing the importance of compliance to optimize outcomes is beneficial.
Warfarin
Patient education is essential before starting warfarin. Patients should be informed about the proper use of warfarin, the need for a regular blood clotting test (international normalized ratio [INR]), and the need for regular follow-up.
Dosing and monitoring of warfarin differs from many other drugs.
Warfarin makes the blood more difficult to clot and, therefore, carries a risk of bleeding.
The effect of the drug is measured with the INR.
Warfarin dose frequently changes over time, and dosing that varies with the day of the week is very common (e.g., 4 mg on Monday, Wednesday, Friday, and Sunday; 5 mg on Tuesday, Thursday, and Saturday).
Dosing is typically referred to in weekly dosing amounts given the day-to-day fluctuations in dose.
The desired or target INR values are generally between 2 and 3.
The INR must be checked (monitored) frequently, with blood tests, often once or twice weekly until the stable dose is reached, then on an extended interval (4-12 weeks) thereafter.
Patients should be instructed on how to handle a missed dose (the approach may vary according to the warfarin manager).
Patients must be very clear about the daily dose of warfarin and the colors of their different warfarin tablets.
A pill organizer can help.
Many drugs interact with warfarin.
The physician/healthcare provider who oversees the warfarin treatment must be notified whenever a new drug (e.g., prescription or over-the-counter drug, supplement, or herbal therapy) is started for the first time, or when a current drug is stopped or the dose is adjusted. NSAIDs should be avoided or used with extreme caution under physician supervision.
Even drugs that do not impact warfarin or alter INR levels may still increase the risk of bleeding through pharmacodynamic interactions (NSAIDs, selective serotonin-reuptake inhibitors).
Diet changes can affect the INR.
Intake of foods with high amounts of vitamin K (e.g., spinach, broccoli) can particularly affect the INR; eating any amount of vegetables or food high in vitamin K is acceptable, so long as the intake is consistent from week to week.
Alcohol should be consumed with caution and only in small amounts. Excess alcohol consumption should be avoided in all patients taking anticoagulants.
Grapefruit juice should be avoided.
Avoid high-risk activities.
Activities that carry a high risk of trauma or serious bleeding should be avoided or, if this is not possible, additional safety precautions should be taken.
Direct oral anticoagulants (DOACs)
DOACs do not require coagulation assay laboratory monitoring. Several drugs can interact with DOACs, leading to increased risk of bleeding or increased risk of thrombosis (e.g., primidone, amiodarone, diltiazem, verapamil, rifampin, phenytoin, phenobarbital, NSAIDs).[319][320] Interactions are most commonly mediated via cytochrome P450 enzyme (CYP450) and/or the transporter permeability glycoprotein (P-gp).[320]
Patients with subsegmental pulmonary embolism and no proximal deep vein thrombosis in the legs who have a low risk for recurrent venous thromboembolism should be informed about clinical signs and symptoms of progressive thrombosis to watch for and the need for reassessment if these are present.[19]
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