Limitations of Use

Warfarin sodium has no direct effect on an established thrombus, nor does it reverse ischemic tissue damage. Once a thrombus has occurred, however, the goals of anticoagulant treatment are to prevent further extension of the formed clot and to prevent secondary thromboembolic complications that may result in serious and possibly fatal sequelae.

2.1 Individualized Dosing

The dosage and administration of warfarin sodium must be individualized for each patient according to the patient's International Normalized Ratio (INR) response to the drug. Adjust the dose based on the patient's INR and the condition being treated. Consult the latest evidence-based clinical practice guidelines regarding the duration and intensity of anticoagulation for the indicated conditions.

2.2 Recommended Target INR Ranges and Durations for Individual Indications

An INR of greater than 4.0 appears to provide no additional therapeutic benefit in most patients and is associated with a higher risk of bleeding.

2.3 Initial and Maintenance Dosing

The appropriate initial dosing of warfarin sodium varies widely for different patients. Not all factors responsible for warfarin dose variability are known, and the initial dose is influenced by:

• Clinical factors including age, race, body weight, sex, concomitant medications, and comorbidities
• Genetic factors (CYP2C9 and VKORC1 genotypes) [see Clinical Pharmacology (12.5)]

Select the initial dose based on the expected maintenance dose, taking into account the above factors. Modify this dose based on consideration of patient-specific clinical factors. Consider lower initial and maintenance doses for elderly and/or debilitated patients and in Asian patients [see Use in Specific Populations (8.5) and Clinical Pharmacology (12.3)]. Routine use of loading doses is not recommended as this practice may increase hemorrhagic and other complications and does not offer more rapid protection against clot formation.

Individualize the duration of therapy for each patient. In general, anticoagulant therapy should be continued until the danger of thrombosis and embolism has passed [see Dosage and Administration (2.2)].

2.4 Monitoring to Achieve Optimal Anticoagulation

Warfarin sodium has a narrow therapeutic range (index), and its action may be affected by factors such as other drugs and dietary vitamin K. Therefore, anticoagulation must be carefully monitored during warfarin sodium therapy. Determine the INR daily after the administration of the initial dose until INR results stabilize in the therapeutic range. After stabilization, maintain dosing within the therapeutic range by performing periodic INRs. The frequency of performing INR should be based on the clinical situation but generally acceptable intervals for INR determinations are 1 to 4 weeks. Perform additional INR tests when other warfarin products are interchanged with warfarin sodium, as well as whenever other medications are initiated, discontinued, or taken irregularly. Heparin, a common concomitant drug, increases the INR [see Dosage and Administration (2.8) and Drug Interactions (7)].

Determinations of whole blood clotting and bleeding times are not effective measures for monitoring of warfarin sodium therapy.

2.5 Renal Impairment

No dosage adjustment is necessary for patients with renal failure. Monitor INR more frequently in patients with compromised renal function to maintain INR within the therapeutic range [see Warnings and Precautions (5.4) and Use in Specific Populations (8.6)].

2.6 Missed Dose

The anticoagulant effect of warfarin sodium persists beyond 24 hours. If a patient misses a dose of warfarin sodium at the intended time of day, the patient should take the dose as soon as possible on the same day. The patient should not double the dose the next day to make up for a missed dose.

2.7 Treatment During Dentistry and Surgery

Some dental or surgical procedures may necessitate the interruption or change in the dose of warfarin sodium therapy. Consider the benefits and risks when discontinuing warfarin sodium even for a short period of time. Determine the INR immediately prior to any dental or surgical procedure. In patients undergoing minimally invasive procedures who must be anticoagulated prior to, during, or immediately following these procedures, adjusting the dosage of warfarin sodium to maintain the INR at the low end of the therapeutic range may safely allow for continued anticoagulation.

2.8 Conversion From Other Anticoagulants

5.1 Hemorrhage

Warfarin sodium can cause major or fatal bleeding. Bleeding is more likely to occur within the first month. Risk factors for bleeding include high intensity of anticoagulation (INR >4.0), age greater than or equal to 65, history of highly variable INRs, history of gastrointestinal bleeding, hypertension, cerebrovascular disease, anemia, malignancy, trauma, renal impairment, certain genetic factors [see Clinical Pharmacology (12.5)], certain concomitant drugs [see Drug Interactions (7)], and long duration of warfarin therapy.

Perform regular monitoring of INR in all treated patients. Those at high risk of bleeding may benefit from more frequent INR monitoring, careful dose adjustment to desired INR, and a shortest duration of therapy appropriate for the clinical condition. However, maintenance of INR in the therapeutic range does not eliminate the risk of bleeding.

Drugs, dietary changes, and other factors affect INR levels achieved with warfarin sodium therapy. Perform more frequent INR monitoring when starting or stopping other drugs, including botanicals, or when changing dosages of other drugs [see Drug Interactions (7)].

Instruct patients about prevention measures to minimize risk of bleeding and to report signs and symptoms of bleeding [see Patient Counseling Information (17)].

5.2 Tissue Necrosis

Warfarin sodium can cause necrosis and/or gangrene of skin and other tissues, which is an uncommon but serious risk (<0.1%). Necrosis may be associated with local thrombosis and usually appears within a few days of the start of warfarin sodium therapy. In severe cases of necrosis, treatment through debridement or amputation of the affected tissue, limb, breast, or penis has been reported.

Careful clinical evaluation is required to determine whether necrosis is caused by an underlying disease. Although various treatments have been attempted, no treatment for necrosis has been considered uniformly effective. Discontinue warfarin sodium therapy if necrosis occurs. Consider alternative drugs if continued anticoagulation therapy is necessary.

5.3 Calciphylaxis

Warfarin sodium can cause fatal and serious calciphylaxis or calcium uremic arteriolopathy, which has been reported in patients with and without end-stage renal disease. When calciphylaxis is diagnosed in these patients, discontinue warfarin sodium and treat calciphylaxis as appropriate. Consider alternative anticoagulation therapy.

5.4 Acute Kidney Injury

In patients with altered glomerular integrity or with a history of kidney disease, acute kidney injury may occur with warfarin sodium, possibly in relation to episodes of excessive anticoagulation and hematuria [see Use in Specific Populations (8.6)]. More frequent monitoring of anticoagulation is advised in patients with compromised renal function.

5.5 Systemic Atheroemboli and Cholesterol Microemboli

Anticoagulation therapy with warfarin sodium may enhance the release of atheromatous plaque emboli. Systemic atheroemboli and cholesterol microemboli can present with a variety of signs and symptoms depending on the site of embolization. The most commonly involved visceral organs are the kidneys followed by the pancreas, spleen, and liver. Some cases have progressed to necrosis or death. A distinct syndrome resulting from microemboli to the feet is known as "purple toes syndrome." Discontinue warfarin sodium therapy if such phenomena are observed. Consider alternative drugs if continued anticoagulation therapy is necessary.

5.6 Limb Ischemia, Necrosis, and Gangrene in Patients with HIT and HITTS

Do not use warfarin sodium as initial therapy in patients with heparin-induced thrombocytopenia (HIT) and with heparin-induced thrombocytopenia with thrombosis syndrome (HITTS). Cases of limb ischemia, necrosis, and gangrene have occurred in patients with HIT and HITTS when heparin treatment was discontinued and warfarin therapy was started or continued. In some patients, sequelae have included amputation of the involved area and/or death. Treatment with warfarin sodium may be considered after the platelet count has normalized.

5.7 Use in Pregnant Women with Mechanical Heart Valves

Warfarin sodium can cause fetal harm when administered to a pregnant woman. While warfarin sodium is contraindicated during pregnancy, the potential benefits of using warfarin sodium may outweigh the risks for pregnant women with mechanical heart valves at high risk of thromboembolism. In those individual situations, the decision to initiate or continue warfarin sodium should be reviewed with the patient, taking into consideration the specific risks and benefits pertaining to the individual patient's medical situation, as well as the most current medical guidelines. Warfarin sodium exposure during pregnancy causes a recognized pattern of major congenital malformations (warfarin embryopathy and fetotoxicity), fatal fetal hemorrhage, and an increased risk of spontaneous abortion and fetal mortality. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus [see Use in Specific Populations (8.1)].

5.8 Other Clinical Settings with Increased Risks

In the following clinical settings, the risks of warfarin sodium therapy may be increased:

• Moderate to severe hepatic impairment
• Infectious diseases or disturbances of intestinal flora (e.g., sprue, antibiotic therapy)
• Use of an indwelling catheter
• Severe to moderate hypertension
• Deficiency in protein C-mediated anticoagulant response: warfarin sodium reduces the synthesis of the naturally occurring anticoagulants, protein C and protein S. Hereditary or acquired deficiencies of protein C or its cofactor, protein S, have been associated with tissue necrosis following warfarin administration. Concomitant anticoagulation therapy with heparin for 5 to 7 days during initiation of therapy with warfarin sodium may minimize the incidence of tissue necrosis in these patients.
• Eye surgery: In cataract surgery, warfarin sodium use was associated with a significant increase in minor complications of sharp needle and local anesthesia block but not associated with potentially sight-threatening operative hemorrhagic complications. As warfarin sodium cessation or reduction may lead to serious thromboembolic complications, the decision to discontinue warfarin sodium before a relatively less invasive and complex eye surgery, such as lens surgery, should be based upon the risks of anticoagulant therapy weighed against the benefits.
• Polycythemia vera
• Vasculitis
• Diabetes mellitus

5.9 Endogenous Factors Affecting INR

The following factors may be responsible for increased INR response: diarrhea, hepatic disorders, poor nutritional state, steatorrhea, or vitamin K deficiency.

The following factors may be responsible for decreased INR response: increased vitamin K intake or hereditary warfarin resistance.

7.1 General Information

Drugs may interact with warfarin sodium through pharmacodynamic or pharmacokinetic mechanisms. Pharmacodynamic mechanisms for drug interactions with warfarin sodium are synergism (impaired hemostasis, reduced clotting factor synthesis), competitive antagonism (vitamin K), and alteration of the physiologic control loop for vitamin K metabolism (hereditary resistance). Pharmacokinetic mechanisms for drug interactions with warfarin sodium are mainly enzyme induction, enzyme inhibition, and reduced plasma protein binding. It is important to note that some drugs may interact by more than one mechanism.

More frequent INR monitoring should be performed when starting or stopping other drugs, including botanicals, or when changing dosages of other drugs, including drugs intended for short-term use (e.g., antibiotics, antifungals, corticosteroids) [see Boxed Warning].

Consult the labeling of all concurrently used drugs to obtain further information about interactions with warfarin sodium or adverse reactions pertaining to bleeding.

7.2 CYP450 Interactions

CYP450 isozymes involved in the metabolism of warfarin include CYP2C9, 2C19, 2C8, 2C18, 1A2, and 3A4. The more potent warfarin S-enantiomer is metabolized by CYP2C9 while the R-enantiomer is metabolized by CYP1A2 and 3A4.

• Inhibitors of CYP2C9, 1A2, and/or 3A4 have the potential to increase the effect (increase INR) of warfarin by increasing the exposure of warfarin.
• Inducers of CYP2C9, 1A2, and/or 3A4 have the potential to decrease the effect (decrease INR) of warfarin by decreasing the exposure of warfarin.

Examples of inhibitors and inducers of CYP2C9, 1A2, and 3A4 are below in Table 2; however, this list should not be considered all-inclusive. Consult the labeling of all concurrently used drugs to obtain further information about CYP450 interaction potential. The CYP450 inhibition and induction potential should be considered when starting, stopping, or changing dose of concomitant medications. Closely monitor INR if a concomitant drug is a CYP2C9, 1A2, and/or 3A4 inhibitor or inducer.

7.3 Drugs that Increase Bleeding Risk

Examples of drugs known to increase the risk of bleeding are presented in Table 3. Because bleeding risk is increased when these drugs are used concomitantly with warfarin, closely monitor patients receiving any such drug with warfarin.

7.4 Antibiotics and Antifungals

There have been reports of changes in INR in patients taking warfarin and antibiotics or antifungals, but clinical pharmacokinetic studies have not shown consistent effects of these agents on plasma concentrations of warfarin.

Closely monitor INR when starting or stopping any antibiotic or antifungal in patients taking warfarin.

7.5 Botanical (Herbal) Products and Foods

More frequent INR monitoring should be performed when starting or stopping botanicals.

Few adequate, well-controlled studies evaluating the potential for metabolic and/or pharmacologic interactions between botanicals and warfarin sodium exist. Due to a lack of manufacturing standardization with botanical medicinal preparations, the amount of active ingredients may vary. This could further confound the ability to assess potential interactions and effects on anticoagulation.

Some botanicals may cause bleeding events when taken alone (e.g., garlic and Ginkgo biloba) and may have anticoagulant, antiplatelet, and/or fibrinolytic properties. These effects would be expected to be additive to the anticoagulant effects of warfarin sodium. Conversely, some botanicals may decrease the effects of warfarin sodium (e.g., co-enzyme Q 10, St. John's wort, ginseng). Some botanicals and foods can interact with warfarin sodium through CYP450 interactions (e.g., echinacea, grapefruit juice, ginkgo, goldenseal, St. John's wort).

The amount of vitamin K in food may affect therapy with warfarin sodium. Advise patients taking warfarin sodium to eat a normal, balanced diet maintaining a consistent amount of vitamin K. Patients taking warfarin sodium should avoid drastic changes in dietary habits, such as eating large amounts of green leafy vegetables.

8.1 Pregnancy

8.2 Lactation

8.3 Females and Males of Reproductive Potential

8.4 Pediatric Use

Adequate and well-controlled studies with warfarin sodium have not been conducted in any pediatric population, and the optimum dosing, safety, and efficacy in pediatric patients is unknown. Pediatric use of warfarin sodium is based on adult data and recommendations, and available limited pediatric data from observational studies and patient registries. Pediatric patients administered warfarin sodium should avoid any activity or sport that may result in traumatic injury.

The developing hemostatic system in infants and children results in a changing physiology of thrombosis and response to anticoagulants. Dosing of warfarin in the pediatric population varies by patient age, with infants generally having the highest, and adolescents having the lowest milligram per kilogram dose requirements to maintain target INRs. Because of changing warfarin requirements due to age, concomitant medications, diet, and existing medical condition, target INR ranges may be difficult to achieve and maintain in pediatric patients, and more frequent INR determinations are recommended. Bleeding rates varied by patient population and clinical care center in pediatric observational studies and patient registries. Infants and children receiving vitamin K-supplemented nutrition, including infant formulas, may be resistant to warfarin therapy, while human milk-fed infants may be sensitive to warfarin therapy.

8.5 Geriatric Use

Of the total number of patients receiving warfarin sodium in controlled clinical trials for which data were available for analysis, 1885 patients (24.4%) were 65 years and older, while 185 patients (2.4%) were 75 years and older. No overall differences in effectiveness or safety were observed between these patients and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Patients 60 years or older appear to exhibit greater than expected INR response to the anticoagulant effects of warfarin [see Clinical Pharmacology (12.3)]. Warfarin sodium is contraindicated in any unsupervised patient with senility. Conduct more frequent monitoring for bleeding with administration of warfarin sodium to elderly patients in any situation or with any physical condition where added risk of hemorrhage is present. Consider lower initiation and maintenance doses of warfarin sodium in elderly patients [see Dosage and Administration (2.2, 2.3)].

8.6 Renal Impairment

Renal clearance is considered to be a minor determinant of anticoagulant response to warfarin. No dosage adjustment is necessary for patients with renal impairment. Instruct patients with renal impairment taking warfarin to monitor their INR more frequently [see Warnings and Precautions (5.4)].

8.7 Hepatic Impairment

Hepatic impairment can potentiate the response to warfarin through impaired synthesis of clotting factors and decreased metabolism of warfarin. Conduct more frequent monitoring for bleeding when using warfarin sodium in these patients.

10.1 Signs and Symptoms

Bleeding (e.g., appearance of blood in stools or urine, hematuria, excessive menstrual bleeding, melena, petechiae, excessive bruising or persistent oozing from superficial injuries, unexplained fall in hemoglobin) is a manifestation of excessive anticoagulation.

10.2 Treatment

The treatment of excessive anticoagulation is based on the level of the INR, the presence or absence of bleeding, and clinical circumstances. Reversal of warfarin sodium anticoagulation may be obtained by discontinuing warfarin sodium therapy and, if necessary, by administration of oral or parenteral vitamin K 1.

The use of vitamin K 1 reduces response to subsequent warfarin sodium therapy and patients may return to a pretreatment thrombotic status following the rapid reversal of a prolonged INR. Resumption of warfarin sodium administration reverses the effect of vitamin K, and a therapeutic INR can again be obtained by careful dosage adjustment. If rapid re-anticoagulation is indicated, heparin may be preferable for initial therapy.

Prothrombin complex concentrate (PCC), fresh frozen plasma, or activated Factor VII treatment may be considered if the requirement to reverse the effects of warfarin sodium is urgent. A risk of hepatitis and other viral diseases is associated with the use of blood products; PCC and activated Factor VII are also associated with an increased risk of thrombosis. Therefore, these preparations should be used only in exceptional or life-threatening bleeding episodes secondary to warfarin sodium overdosage.

12.1 Mechanism of Action

Warfarin acts by inhibiting the synthesis of vitamin K-dependent clotting factors, which include Factors II, VII, IX, and X, and the anticoagulant proteins C and S. Vitamin K is an essential cofactor for the post ribosomal synthesis of the vitamin K-dependent clotting factors. Vitamin K promotes the biosynthesis of γ-carboxyglutamic acid residues in the proteins that are essential for biological activity. Warfarin is thought to interfere with clotting factor synthesis by inhibition of the C1 subunit of vitamin K epoxide reductase (VKORC1) enzyme complex, thereby reducing the regeneration of vitamin K 1 epoxide [see Clinical Pharmacology (12.5)].

12.2 Pharmacodynamics

An anticoagulation effect generally occurs within 24 hours after warfarin administration. However, peak anticoagulant effect may be delayed 72 to 96 hours. The duration of action of a single dose of racemic warfarin is 2 to 5 days. The effects of warfarin sodium may become more pronounced as effects of daily maintenance doses overlap. This is consistent with the half-lives of the affected vitamin K-dependent clotting factors and anticoagulation proteins: Factor II - 60 hours, VII - 4 to 6 hours, IX - 24 hours, X - 48 to 72 hours, and proteins C and S are approximately 8 hours and 30 hours, respectively.

12.3 Pharmacokinetics

Warfarin sodium is a racemic mixture of the R- and S-enantiomers of warfarin. The S-enantiomer exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer in humans, but generally has a more rapid clearance.

12.5 Pharmacogenomics

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenicity, mutagenicity, or fertility studies have not been performed with warfarin.

14.1 Atrial Fibrillation

In five prospective, randomized, controlled clinical trials involving 3711 patients with non-rheumatic AF, warfarin significantly reduced the risk of systemic thromboembolism including stroke (see Table 4). The risk reduction ranged from 60% to 86% in all except one trial (CAFA: 45%), which was stopped early due to published positive results from two of these trials. The incidence of major bleeding in these trials ranged from 0.6% to 2.7% (see Table 4).

Trials in patients with both AF and mitral stenosis suggest a benefit from anticoagulation with warfarin sodium [see Dosage and Administration (2.2)].

14.2 Mechanical and Bioprosthetic Heart Valves

In a prospective, randomized, open-label, positive-controlled study in 254 patients with mechanical prosthetic heart valves, the thromboembolic-free interval was found to be significantly greater in patients treated with warfarin alone compared with dipyridamole/aspirin-treated patients (p<0.005) and pentoxifylline/aspirin-treated patients (p<0.05). The results of this study are presented in Table 5.

In a prospective, open-label, clinical study comparing moderate (INR 2.65) versus high intensity (INR 9.0) warfarin therapies in 258 patients with mechanical prosthetic heart valves, thromboembolism occurred with similar frequency in the two groups (4.0 and 3.7 events per 100 patient years, respectively). Major bleeding was more common in the high intensity group. The results of this study are presented in Table 6.

In a randomized trial in 210 patients comparing two intensities of warfarin therapy (INR 2.0 to 2.25 vs. INR 2.5 to 4.0) for a three-month period following tissue heart valve replacement, thromboembolism occurred with similar frequency in the two groups (major embolic events 2.0% vs. 1.9%, respectively, and minor embolic events 10.8% vs. 10.2%, respectively). Major hemorrhages occurred in 4.6% of patients in the higher intensity INR group compared to zero in the lower intensity INR group.

14.3 Myocardial Infarction

WARIS (The Warfarin Re-Infarction Study) was a double-blind, randomized study of 1214 patients 2 to 4 weeks post-infarction treated with warfarin to a target INR of 2.8 to 4.8. The primary endpoint was a composite of total mortality and recurrent infarction. A secondary endpoint of cerebrovascular events was assessed. Mean follow-up of the patients was 37 months. The results for each endpoint separately, including an analysis of vascular death, are provided in Table 7.

WARIS II (The Warfarin, Aspirin, Re-Infarction Study) was an open-label, randomized study of 3630 patients hospitalized for acute myocardial infarction treated with warfarin to a target INR 2.8 to 4.2, aspirin 160 mg per day, or warfarin to a target INR 2.0 to 2.5 plus aspirin 75 mg per day prior to hospital discharge. The primary endpoint was a composite of death, nonfatal reinfarction, or thromboembolic stroke. The mean duration of observation was approximately 4 years. The results for WARIS II are provided in Table 8.

There were approximately four times as many major bleeding episodes in the two groups receiving warfarin than in the group receiving aspirin alone. Major bleeding episodes were not more frequent among patients receiving aspirin plus warfarin than among those receiving warfarin alone, but the incidence of minor bleeding episodes was higher in the combined therapy group.

Protect from light and moisture. Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Dispense in a tight, light-resistant container as defined in the USP.

Store the hospital unit-dose blister packages in the carton until contents have been used.

Special Handling

Procedures for proper handling and disposal of potentially hazardous drugs should be considered. Guidelines on this subject have been published [see References (15)].

Pharmacy and clinical personnel who are pregnant should avoid exposure to crushed or broken tablets [see Use in Specific Populations (8.1)].

Instructions for Patients

Advise patients to:

• Strictly adhere to the prescribed dosage schedule [see Dosage and Administration (2.1)].
• If the prescribed dose of warfarin sodium is missed, take the dose as soon as possible on the same day but do not take a double dose of warfarin sodium the next day to make up for missed doses [see Dosage and Administration (2.6)].
• Obtain prothrombin time tests and make regular visits to their physician or clinic to monitor therapy [see Dosage and Administration (2.1)].
• Be aware that if therapy with warfarin sodium is discontinued, the anticoagulant effects of warfarin sodium may persist for about 2 to 5 days [see Clinical Pharmacology (12.2)].
• Avoid any activity or sport that may result in traumatic injury [see Use in Specific Populations (8.4)]. And to tell their physician if they fall often as this may increase their risk for complications.
• Eat a normal, balanced diet to maintain a consistent intake of vitamin K. Avoid drastic changes in dietary habits, such as eating large amounts of leafy, green vegetables [see Drug Interactions (7.5)].
• Contact their physician to report any serious illness, such as severe diarrhea, infection, or fever [see Warnings and Precautions (5) and Adverse Reactions (6)].
• Immediately contact their physician when experiencing pain and discoloration of the skin (a purple bruise like rash) mostly on areas of the body with a high fat content, such as breasts, thighs, buttocks, hips and abdomen [see Warnings and Precautions (5.2)].
• Immediately contact their physician when experiencing any unusual symptom or pain since warfarin sodium may cause small cholesterol or athero emboli. On feet it may appear as a sudden cool, painful, purple discoloration of toe(s) or forefoot [see Warnings and Precautions (5.5)].
• Immediately contact their physician when taking warfarin sodium after any heparin formulation therapy and experiencing bloody or black stools or appearence of bruises, or bleeding [see Warnings and Precautions (5.6)].
• To tell all of their healthcare professionals and dentists that they are taking warfarin sodium. This should be done before they have any surgery or dental procedure [see Dosage and Administration (2.7)].
• Carry identification stating that they are taking warfarin sodium.

Bleeding Risks

Advise patients to:

• Notify their physician immediately if any unusual bleeding or symptoms occur. Signs and symptoms of bleeding include: pain, swelling or discomfort, prolonged bleeding from cuts, increased menstrual flow or vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or dark brown urine, red or tar black stools, headache, dizziness, or weakness [see Box Warning and Warnings and Precautions (5.1)].

Concomitant Medications and Botanicals (Herbals)

Advise patients to:

• Not take or discontinue any other drug, including salicylates (e.g., aspirin and topical analgesics), other over-the-counter drugs, and botanical (herbal) products except on advice of your physician [see Drug Interactions (7)].

Pregnancy and Nursing

Advise patients to:

• Notify their physician if they are pregnant or planning to become pregnant or considering breast feeding [see Use in Specific Populations (8.1, 8.2, 8.3)].
• Avoid warfarin sodium during pregnancy except in pregnant women with mechanical heart valves, who are at risk of thromboembolism [see Contraindications (4)]. Use effective measures to avoid pregnancy while taking warfarin sodium. This is very important because their unborn baby could be seriously harmed if they take warfarin sodium while they are pregnant [see Use in Specific Populations (8.1, 8.3)].