Warf (Warfarin Sodium)
Also sold as: Warf, Coumadin, Cofarin, Warfin, Uniwarfin
Pregnancy
Cat X
Lactation
Safe
Schedule
H
Forms
Tablet 1mg, 2mg, 5mg
Indications
- Atrial fibrillation — stroke prevention (especially valvular AF)
- Mechanical prosthetic heart valves (ESSENTIAL — DOACs contraindicated)
- DVT / PE treatment and secondary prevention
- Antiphospholipid syndrome
- Rheumatic heart disease with AF
Adult Dosing
Initiation
5 mg PO OD for 2 days; adjust based on INR
Elderly, liver disease, heart failure, interacting drugs: start 2-3 mg. Check INR on Day 3-4 and adjust.
Maintenance
2-10 mg PO OD (highly individualised based on INR)
Target INR: AF/DVT/PE = 2.0-3.0; Mechanical mitral valve = 2.5-3.5; Mechanical aortic = 2.0-3.0
Pediatric Dosing
ALWAYS under haematology/cardiology specialist guidance. INR-guided dosing essential.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| CKD | Start low (2 mg); INR monitoring more frequent — bleeding risk elevated |
Hepatic Adjustment
Start very low — hepatic impairment reduces clotting factor synthesis; INR may be elevated at baseline. Extreme caution.
Pregnancy & Lactation
Pregnancy: Category X
CONTRAINDICATED in 1st trimester (warfarin embryopathy — nasal hypoplasia, stippled epiphyses, limb defects). Crosses placenta — fetal haemorrhage. Use LMWH (enoxaparin) throughout pregnancy. Exception: mechanical heart valves in 2nd trimester under careful monitoring (maternal life priority).
Lactation: Safe
Does not pass into breast milk in significant amounts. Safe to breastfeed on warfarin.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Hundreds of interactions — warfarin is most drug-interacting anticoagulant | Any new drug should trigger INR recheck within 3-7 days | Major |
| Antibiotics (metronidazole, fluconazole, ciprofloxacin, co-trimoxazole) | Increase INR significantly — major bleeding risk | Major |
| NSAIDs / Aspirin | Increase bleeding risk (platelet inhibition + GI mucosal damage) | Major |
| Amiodarone | Doubles warfarin levels — reduce warfarin dose by 30-50% when starting amiodarone | Major |
| Rifampicin / Carbamazepine / Phenytoin | Enzyme inducers — dramatically reduce warfarin levels; INR falls | Major |
| Vitamin K (diet — leafy greens) | Reduces anticoagulant effect; consistent intake is key — do not avoid, just be consistent | Moderate |
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Side Effects
Common
- Bleeding (minor: bruising, nosebleeds, prolonged cuts)
- Skin necrosis (rare, 3-8 days of initiation — protein C deficiency)
- Alopecia (rare)
Serious / Discontinue If
- Major bleeding: intracranial (most feared), GI, retroperitoneal
- Warfarin-induced skin necrosis (protein C/S deficiency)
- Purple toe syndrome (cholesterol embolism)
Contraindications
- Active major bleeding
- Pregnancy (1st trimester and near term)
- Severe uncontrolled hypertension
- Recent neurosurgery/eye surgery
- High fall risk in elderly (relative)
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Warf 5mg | Cipla | 30 tab ₹45 |
| Warf 2mg | Cipla | 30 tab ₹38 |
| Cofarin 5mg | Sun Pharma | 30 tab ₹42 |
| Warfin 5mg | Emcure | 30 tab ₹38 |
Monitoring Required
- INR — initially daily until stable, then weekly, then monthly (stable patients every 4-12 weeks)
- Target INR ranges: AF/DVT/PE 2.0-3.0; mechanical valves 2.5-3.5
- CBC (Hb, platelets)
- Signs of bleeding or thromboembolic events
- Time in Therapeutic Range (TTR) — target > 65-70%
Patient Counseling Points
- Take at the SAME TIME every day (evening — allows morning INR review and dose change)
- NEVER miss your INR blood test — this is as important as taking the tablet
- Maintain CONSISTENT vitamin K diet — do not suddenly increase or reduce leafy greens
- Inform ALL doctors, dentists, pharmacists about warfarin before any drug is added
- Carry anticoagulant card at all times
- Report any unusual bleeding — gums, urine (red/brown), stool (black/red), prolonged cuts
- Head injury: go to A&E immediately even if no symptoms (intracranial bleed risk)
Stop Googling drug references mid-consultation
EasyClinic auto-flags Warf interactions, renal cutoffs, and pregnancy warnings the moment you write the prescription. Built-in safety net for every Indian doctor.
Clinically reviewed by: Dr. Priya Sharma, DM (Cardiology), Senior Cardiologist
Last reviewed: 2026-04-01
References
- BNF — Warfarin
- ESC AF Guidelines 2023
- ACCP Antithrombotic Guidelines 2021
- BSH Oral Anticoagulation Guidelines