What is the maximum dose of Coumadin (warfarin) that can be taken at once?

From the Guidelines

The maximum dose of Coumadin (warfarin) that can be taken at once is not established, and dosing should be highly individualized based on each patient's response to the medication, with typical daily doses ranging from 1 to 10 mg. Warfarin dosing is typically initiated with 10 mg daily for the first 2 days, followed by dosing based on INR measurements, as suggested by the American College of Chest Physicians evidence-based clinical practice guidelines 1. The appropriate dose is determined by monitoring the International Normalized Ratio (INR), which measures blood clotting time, with target INR ranges typically between 2.0-3.0 or 2.5-3.5 depending on the condition being treated. Some key points to consider when taking warfarin include:

• Taking more warfarin than prescribed can be extremely dangerous and potentially fatal, as it can cause severe bleeding complications
• Warfarin has a narrow therapeutic window, meaning the difference between an effective dose and a harmful dose is small
• Dosing adjustments should only be made under medical supervision, and patients should never increase their dose without consulting their healthcare provider
• If a dose is missed, patients should follow their provider's instructions rather than taking extra medication to "catch up"
• Regular INR monitoring is essential for safe warfarin therapy, as emphasized in the guidelines 1.

From the FDA Drug Label

The patient should not double the dose the next day to make up for a missed dose. The maximum dose of Coumadin (warfarin) that can be taken at once is not explicitly stated in the drug label. However, it is recommended that if a patient misses a dose, they should take the dose as soon as possible on the same day and not double the dose the next day.

• Typical maintenance doses are 2 to 10 mg once daily.
• Initial dose is usually 2 to 5 mg once daily. 2 2

From the Research

Maximum Dose of Coumadin (Warfarin)

The maximum dose of Coumadin (warfarin) that can be taken at once is not explicitly stated in the provided studies. However, the following information can be gathered:

• When initiating warfarin therapy, clinicians should avoid loading doses that can raise the International Normalized Ratio (INR) excessively; instead, warfarin should be initiated with a 5-mg dose (or 2 to 4 mg in the very elderly) 3.
• Therapeutic doses of warfarin range from 1 mg to 10 mg/day 4.
• The total weekly dose of warfarin is positively correlated with body mass index (BMI), with an increase of 0.69 mg in the weekly warfarin dose for each 1-point increase in BMI 5.

Factors Affecting Warfarin Dosing

Several factors can affect warfarin dosing, including:

• Genetic variation, such as cytochrome P4502C9 and Vitamin K Epoxide Reductase Complex (VKORC) polymorphisms 4.
• Physiologic factors, such as diet and medications 4.
• Patient characteristics, such as age and weight 3, 5.
• International Normalized Ratio (INR) values, which should be monitored frequently to adjust the warfarin dose 3.

Important Considerations

• The risk of bleeding increases exponentially with INR and becomes clinically unacceptable once the INR exceeds 5.0 6.
• Warfarin therapy should be continued for a specific duration, depending on the clinical condition, such as 6 weeks for symptomatic calf vein thrombosis or 3-6 months after proximal deep vein thrombosis (DVT) 6.