Vitamin K antagonist Pregnancy: Contraindicated in pregnancy; may cause congenital malformations. Women of child-bearing potential should use contraception.

Acenocoumarol

Brand names: Sinthrome

Acenocoumarol is an oral coumarin anticoagulant used to prevent and treat thromboembolic disorders.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 2-4 mg

Route: Oral

Frequency: Once daily

Usual starting dose 2-4 mg/day without a loading dose; alternatively a loading regimen of 6 mg on day 1 then 4 mg on day 2. Dosing must be individualised to PT/INR. Maintenance dose generally 1-8 mg daily; target INR usually 2.0-3.5 depending on indication (2.0-3.0 for VTE, AF, post-MI, bioprosthetic valves; 2.0-3.5 for mechanical valves and antiphospholipid syndrome with VTE). Elderly (>=65), liver disease, severe heart failure with hepatic congestion or malnourished patients may need lower doses.

Dose adjustments

Renal

Contraindicated in severe renal impairment; caution in mild to moderate renal impairment due to possible metabolite accumulation.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known hypersensitivity to acenocoumarol, related coumarin derivatives, or any excipient
Pregnancy
Patients unable to co-operate and who are unsupervised (e.g. unsupervised senile patients, alcoholics, psychiatric disorders)
Haemorrhagic diathesis or haemorrhagic blood dyscrasia
Shortly before or after surgery on the CNS, eyes, or traumatising surgery with extensive tissue exposure
Peptic ulcers or haemorrhage of the GI, urogenital or respiratory tract; cerebrovascular haemorrhage; acute pericarditis; pericardial effusion; infective endocarditis
Severe hypertension
Severe hepatic impairment
Severe renal impairment
Increased fibrinolytic activity (e.g. after operations on lung, prostate or uterus)

Side effects

Haemorrhage (most common; various organ sites, can be fatal)
Hypersensitivity (urticaria, rash, dermatitis, fever)
Decreased appetite, nausea, vomiting
Alopecia
Haemorrhagic skin necrosis (usually with congenital protein C/S deficiency)
Anaemia secondary to haemorrhage; anticoagulant-related nephropathy; calciphylaxis

Clinical monograph

How it works

It inhibits vitamin K epoxide reductase, reducing regeneration of active vitamin K and thereby the hepatic synthesis of clotting factors II, VII, IX and X.

Prescribing in practice

The dose must be individualised and adjusted to the INR because of a narrow therapeutic window and a high risk of bleeding.
It interacts with numerous drugs, foods and conditions that alter its effect, so review concomitant therapy carefully.
It is teratogenic and generally contraindicated in pregnancy.

Monitoring

Monitor INR regularly and adjust the dose to keep it within the target range for the indication.

Counselling the patient

Attend all INR blood tests and follow dose changes exactly as instructed.
Report any unusual bleeding or bruising promptly.
Tell healthcare professionals you take an anticoagulant before any procedure or new medicine.

Evidence & guidelines

Vitamin K antagonists such as acenocoumarol have a long-established evidence base for preventing thromboembolism, with dosing guided by INR.

Reference: BSH oral anticoagulant guideline 2011/2024 update; SmPC Sinthrome; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Drugs

Warfarin · Vitamin K Antagonist

Pathways