pharmacopeia
GET
/api/v1/drug/warfarin

Boxed warning

BLEEDING RISK Warfarin sodium can cause major or fatal bleeding [see Warnings and Precautions ( 5.1 )] . Perform regular monitoring of INR in all treated patients [see Dosage and Administration ( 2.1 )] . Drugs, dietary changes, and other factors affect INR levels achieved with warfarin sodium therapy [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 )] . WARNING: BLEEDING RISK See full prescribing information for complete boxed warning. Warfarin sodium can cause major or fatal bleeding. ( 5.1 ) Perform regular monitoring of INR in all treated patients. ( 2.1 ) Drugs, dietary changes, and other factors affect INR levels achieved with warfarin sodium therapy. ( 7 ) Instruct patients about prevention measures to minimize risk of bleeding and to report signs and symptoms of bleeding. ( 17 )

2D structure
4-hydroxy-3-(3-oxo-1-phenylbutyl)chromen-2-one
SMILES CC(=O)CC(C1=CC=CC=C1)C2=C(C3=CC=CC=C3OC2=O)O
InChIKey PJVWKTKQMONHTI-UHFFFAOYSA-N

Mechanism of action

Sourced from openFDA

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 KVitamin K Epoxide Reductase

Indications

Sourced from openFDA
  • Warfarin sodium tablets are indicated for: Prophylaxis and treatment of venous thrombosis and its extension, pulmonary embolism (PE). Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation (AF) and/or cardiac valve replacement.ICD-10: I26.99, I48.91

Contraindications

Sourced from openFDA
  • Warfarin sodium is contraindicated in: Pregnancy Warfarin sodium is contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism [see Warnings and Precautions ( 5.7 ) and Use in Specific Populations ( 8.1 )] . Warfarin sodium can cause fetal harm when administered to a pregnant woman.contraindicated

Dosage & administration

Sourced from openFDA

Individualize dosing regimen for each patient, and adjust based on INR response. ( 2.1 , 2.2 ) Knowledge of genotype can inform initial dose selection. ( 2.3 ) Monitoring: Obtain daily INR determinations upon initiation until stable in the therapeutic range. Obtain subsequent INR determinations every 1 to 4 weeks. ( 2.4 ) Review conversion instructions from other anticoagulants. ( 2.8 ) 2.1 Individualized Dosing The dosage and administration of warfarin sodium tablets 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 appears to provide no additional therapeutic benefit in most patients and is associated with a higher risk of bleeding. Venous Thromboembolism (including deep venous thrombosis [DVT] and PE) Adjust the warfarin dose to maintain a target INR of 2.5 (INR range, 2 to 3) for all treatment durations. The duration of treatment is based on the indication as follows: For patients with a DVT or PE secondary to a transient (reversible) risk factor, treatment with warfarin for 3 months is recommended. For patients with an unprovoked DVT or PE, treatment with warfarin is recommended for at least 3 months.

Warnings & precautions

Sourced from openFDA

Tissue necrosis: Necrosis or gangrene of skin or other tissues can occur, with severe cases requiring debridement or amputation. Discontinue warfarin sodium and consider alternative anticoagulants if necessary. ( 5.2 ) Calciphylaxis: Fatal and serious cases have occurred. Discontinue warfarin sodium and consider alternative anticoagulation therapy. ( 5.3 ) Acute kidney injury may occur during episodes of excessive anticoagulation and hematuria. ( 5.4 ) Systemic atheroemboli and cholesterol microemboli: Some cases have progressed to necrosis or death. Discontinue warfarin sodium if such emboli occur. ( 5.5 ) Heparin-induced thrombocytopenia (HIT): Initial therapy with warfarin sodium in HIT has resulted in cases of amputation and death. Warfarin sodium may be considered after platelet count has normalized. ( 5.6 ) Pregnant women with mechanical heart valves: Warfarin sodium may cause fetal harm; however, the benefits may outweigh the risks. ( 5.7 ) 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), 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.

Adverse reactions

Sourced from openFDA

The following serious adverse reactions to warfarin sodium are discussed in greater detail in other sections of the labeling: Hemorrhage [see Boxed Warning, Warnings and Precautions (5.1), and Overdosage ( 10 )] Tissue Necrosis [see Warnings and Precautions ( 5.2 )] Calciphylaxis [see Warnings and Precautions ( 5.3 )] Acute Kidney Injury [see Warnings and Precautions ( 5.4 )] Systemic Atheroemboli and Cholesterol Microemboli [see Warnings and Precautions ( 5.5 )] Limb Ischemia, Necrosis, and Gangrene in Patients with HIT and HITTS [see Warnings and Precautions ( 5.6 )] Other Clinical Settings with Increased Risks [see Warnings and Precautions ( 5.8 )] Other adverse reactions to warfarin sodium include: Immune system disorders: hypersensitivity/allergic reactions (including urticaria and anaphylactic reactions) Vascular disorders: vasculitis Hepatobiliary disorders: hepatitis, elevated liver enzymes. Cholestatic hepatitis has been associated with concomitant administration of warfarin sodium and ticlopidine. Gastrointestinal disorders: nausea, vomiting, diarrhea, taste perversion, abdominal pain, flatulence, bloating Skin disorders: rash, dermatitis (including bullous eruptions), pruritus, alopecia Respiratory disorders: tracheal or tracheobronchial calcification General disorders: chills Most common adverse reactions to warfarin sodium are fatal and nonfatal hemorrhage from any tissue or organ. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Teva at 1-888-838-2872 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Use in specific populations

Sourced from openFDA

Pregnant women with mechanical heart valves: Warfarin sodium may cause fetal harm; however, the benefits may outweigh the risks. ( 8.1 ) Lactation: Monitor breastfeeding infants for bruising or bleeding. ( 8.2 ) Renal Impairment: Instruct patients with renal impairment to frequently monitor their INR. ( 8.6 ) 8.1 Pregnancy Risk Summary Warfarin sodium is contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism, and for whom the benefits of warfarin sodium may outweigh the risks [see Warnings and Precautions ( 5.7 )] . Warfarin sodium can cause fetal harm. Exposure to warfarin during the first trimester of pregnancy caused a pattern of congenital malformations in about 5% of exposed offspring. Because these data were not collected in adequate and well-controlled studies, this incidence of major birth defects is not an adequate basis for comparison to the estimated incidences in the control group or the U.S. general population and may not reflect the incidences observed in practice. Consider the benefits and risks of warfarin sodium and possible risks to the fetus when prescribing warfarin sodium to a pregnant woman. Adverse outcomes in pregnancy occur regardless of the health of the mother or the use of medications.

Pharmacokinetics

Sourced from openFDA
Metabolism
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.

Overdosage

Sourced from openFDA

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.

Approval history

Sourced from openFDA
  • Jul 15, 1999ANDAANDA040301Taro
  • Oct 2, 2003ANDAANDA040416Upsher Smith Labs
  • Jul 5, 2006ANDAANDA040616Pliva
  • May 25, 2011ANDAANDA090935Invagen Pharms
  • Mar 4, 2013ANDAANDA202202Amneal Pharms

FAERS reports

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Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
126,799 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
  1. 1International Normalised Ratio Increased10,4088.2%
  2. 2Dyspnoea8,5086.7%
  3. 3Drug Interaction6,3535.0%
  4. 4Fatigue6,2544.9%
  5. 5Nausea6,0004.7%
  6. 6Diarrhoea5,9924.7%
  7. 7Dizziness5,2444.1%
  8. 8Drug Ineffective5,2064.1%
  9. 9Fall4,8813.8%
  10. 10Death4,7903.8%
  11. 11Headache4,7273.7%
  12. 12Asthenia4,4203.5%
  13. 13Pneumonia4,1433.3%
  14. 14Haemorrhage4,0713.2%
  15. 15Anaemia3,9683.1%

Literature

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Recent PubMed references pinned to Warfarin as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

Clinical trials

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The 10 most recently updated of 774 ClinicalTrials.gov registrations naming Warfarin as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

Pharmacogenomics

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CPIC-curated drug–gene pairs for Warfarin. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

Structural analogs

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Ranked by 2D fingerprint (Tanimoto) similarity over PubChem structures. Structural proximity only — not a claim of therapeutic equivalence.

Frequently asked questions

How does Warfarin work?
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.
What is Warfarin used for?
According to FDA labeling, Warfarin carries indications including: Warfarin sodium tablets are indicated for: Prophylaxis and treatment of venous thrombosis and its extension, pulmonary embolism (PE). Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation (AF) and/or cardiac valve replacement.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
What class of drug is Warfarin?
Warfarin is classified as Vitamin K antagonists, Vitamin K Antagonist, Vitamin K Epoxide Reductase Inhibitors, Vitamin K Inhibitors, Decreased Coagulation Factor Activity, Decreased Coagulation Factor Concentration.
What are the brand names for Warfarin?
Warfarin is marketed under brand names including Coumadin, Jantoven.
What are the contraindications for Warfarin?
Warfarin labeling lists contraindications including: Warfarin sodium is contraindicated in: Pregnancy Warfarin sodium is contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism [see Warnings and Precautions ( 5.7 ) and Use in Specific Populations ( 8.1 )] . Warfarin sodium can cause fetal harm when administered to a pregnant woman.. Always consult the full prescribing information and a clinician.
Note. Data for warfarin is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.

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