phenindione at a glance
Medicine class
Vitamin K antagonist anticoagulant
Main role
Prevention and treatment of specified harmful blood clots
Monitoring
Regular INR blood tests are essential
Important precaution
Tell healthcare professionals, including dentists, that you take phenindione
What is phenindione used for?
UK-licensed uses for the selected product are:
Preventing systemic embolism associated with rheumatic heart disease and atrial fibrillation
Preventing clots after insertion of a prosthetic heart valve
Preventing and treating venous thrombosis
Preventing and treating pulmonary embolism
How does phenindione work?
Phenindione interferes with vitamin K-dependent production of clotting factors II, VII, IX and X. This makes blood take longer to clot, helping prevent existing clots growing and new harmful clots forming. Its effect is delayed because clotting factors already present must first be cleared.
phenindione preparations and strengths
Tablet
Route: Oral
Strengths: 10 mg, 25 mg
How to take phenindione
Take phenindione exactly as directed by the anticoagulation service and follow the current instructions in your anticoagulant record.
Swallow the tablet with water; the score line on the selected tablet is not intended for splitting.
Carry your anticoagulant card and show it to doctors, pharmacists and dentists.
Keep your diet reasonably consistent and discuss major dietary changes, supplements or herbal products with the anticoagulation service.
Do not stop phenindione without medical advice.
phenindione side effects
Common or expected effects
- Minor bruising or bleeding
- Nausea, vomiting or diarrhoea
- Altered taste
- Heavier menstrual bleeding
- Pink or orange urine caused by phenindione metabolites; blood in urine must still be excluded
Get urgent medical advice
- Major, persistent or unexplained bleeding
- Bleeding in the brain, chest or digestive tract
- Severe allergic reaction or serious skin reaction
- Skin necrosis, painful dark skin or blue toe syndrome
- Jaundice or other signs of liver injury
- Blood-cell disorders, sometimes presenting with fever, infections, marked weakness or tiredness
- Severe abdominal or back pain, which may indicate pancreatitis
phenindione in pregnancy
Phenindione is contraindicated during pregnancy because it may harm the fetus and cause fetal bleeding, particularly near delivery. Anyone planning pregnancy or who may be pregnant should contact their prescriber promptly so specialist anticoagulation can be arranged.
phenindione while breastfeeding
Breastfeeding is contraindicated with the selected phenindione product because phenindione enters breast milk. Specialist advice is needed about an alternative; SPS identifies warfarin as the preferred oral anticoagulant during breastfeeding when clinically appropriate.
phenindione interactions
Phenindione has many clinically important interactions. Check all prescribed, over-the-counter and complementary products with the anticoagulation service.
Aspirin and NSAIDs, including ibuprofen and naproxen
They can substantially increase bleeding risk and should not be used unless a clinician has specifically advised it.
Other anticoagulants and antiplatelets
Medicines such as heparins, direct oral anticoagulants or clopidogrel increase bleeding risk and require specialist management.
Thrombolytics
Streptokinase and alteplase are contraindicated because of the risk of severe bleeding.
Common questions about phenindione
Answers are fully visible for fast scanning and source review.
Why is phenindione prescribed?
It is prescribed to prevent or treat specified harmful blood clots, including venous thrombosis, pulmonary embolism and embolism associated with certain heart conditions or prosthetic valves.
Why does phenindione require INR blood tests?
The INR shows how long blood takes to clot and helps the anticoagulation service keep phenindione's effect within the intended range.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.