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Warfarin

Medication vitamin K antagonist anticoagulant heart & blood pressure
Aka: Coumadin, Marevan
Brands seen in Singapore: Marevan, Apo-Warfarin
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Preventing and treating blood clots
When to take
Once a day at the SAMe time each day (HealthHub)
Take with
With or without food · vitamin K intake kept steady
Pros & cons
Pros
  • The dose is set by a regular INR blood test
  • SG marevan: 1 mg brown, 3 mg blue, 5 mg pink tablets
  • NHS: an anticoagulant alert card comes with it
Cons
  • Bleeding is the main side effect (NHS)
  • INR tests are daily to weekly at first (NHS)
  • Food, herbs and many medicines shift the INR
Sources
  1. HSA — Listing of Registered Therapeutic Products (data.gov.sg dataset d_767279312753558cbf19d48344577084), Forensicclassification column; all 5,511 rows pulled once via the datastore_search API and filtered locally, 27 Aug 2026 · read 2026-08-27
    what it says
    “MAREVAN TABLET 1 mg SIN08146P | Prescription Only; MAREVAN 3 mg SIN08019P; MAREVAN 5 mg SIN08147P; Apo-Warfarin 1mg SIN13515P; 2mg SIN13516P; 5mg SIN13517P — all 6 warfarin rows 'Prescription Only'; no COUMADIN row.”
  2. MOH National Drug Formulary (Singapore) — MAREVAN TABLET 5 MG (NEW ZEALAND) [SIN08147P], warfarin sodium, Apex Pharma Marketing — product info and forensic classification · read 2026-08-27
    what it says
    “WARFARIN SODIUM - 5 MG … TABLET … Forensic Classification: PRESCRIPTION ONLY MEDICINES … Anatomical Therapeutic Chemical (ATC) code B01AA03 … Prescription-only Medicines with Exemptions for Supply without Prescription: NA”
  3. MOH National Drug Formulary (Singapore) — MAREVAN [SIN08147P], indications · read 2026-08-27
    what it says
    “Prophylaxis of systemic embolisation in patients with rheumatic heart disease and atrial fibrillation. Prophylaxis of thromboembolism after insertion of prosthetic heart valves. Prophylaxis and treatment of venous thrombosis and pulmonary embolism. Transient attacks of cerebral ischaemia.”
  4. MOH National Drug Formulary (Singapore) — MAREVAN [SIN08147P], dosage and administration · read 2026-08-27
    what it says
    “The typical induction dose is 10 mg daily for 2 days … The daily maintenance dose is usually 3 to 9 mg taken at the same time each day. The exact maintenance dose depends on the prothrombin time”
  5. MOH National Drug Formulary (Singapore) — MAREVAN [SIN08147P], contraindications · read 2026-08-27
    what it says
    “Warfarin is contraindicated in: … Clinically significant bleeding, Within 72 hours of major surgery with risk of severe bleeding, Within 48 hours postpartum, Pregnancy (first and third trimesters) … Severe hepatic or renal disease … hypertension, gastrointestinal ulcerations”
  6. HealthHub (MOH Singapore) — Warfarin, last reviewed 17 October 2025 (uses, brand, INR monitoring, administration) · read 2026-08-27
    what it says
    “Warfarin is an anticoagulant … It works by blocking the action of Vitamin K in the liver … The most common brand available in Singapore is Marevan®. There are 3 colours and strengths: 1mg (brown), 3mg (blue), 5mg (pink)”
  7. HealthHub (MOH Singapore) — Warfarin, dietary and medication interactions section · read 2026-08-27
    what it says
    “A change in the Vitamin K intake from your diet will affect the INR result … Avoid any form of traditional or herbal remedies (e.g. ginseng soup, herbal “Bak Kut Teh”, herbal jelly)”
  8. NHS medicines A–Z — Warfarin (page last reviewed 24 February 2026) · read 2026-08-27
    what it says
    “The main side effect of warfarin is an increased risk of bleeding … blood tests every day or every few days … only need a test every 12 weeks once you're on a stable dose … an anticoagulant alert card”
  9. NHS medicines A–Z — Warfarin, taking it with other medicines, food and drink · read 2026-08-27
    what it says
    “NSAIDs, such as ibuprofen or aspirin … antibiotics … antidepressants … medicines for fungal infections … statins … Do not take the herbal remedy St John's wort or vitamin K supplements … do not have cranberry juice … grapefruit juice”
  10. HealthHub (MOH Singapore) — Warfarin, alcohol advice within the dietary interactions section · read 2026-08-27
    what it says
    “Avoid excessive alcohol consumption. It is advisable to take no more than 1 can/glass of beer or wine per day. Avoid strong alcoholic drinks (e.g. whisky, brandy) as this can cause changes to the effect of warfarin.”
  11. HealthHub SG — Warfarin (vitamin K and diet) · read 2026-08-29
    what it says
    “Maintain a consistent diet in terms of your daily portions of vitamin K-rich food to ensure consistency in Vitamin K intake … It is not necessary to avoid these foods entirely as many of them are good for health.”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.