Blood thinners are medicines that many of us take in our lives whether for a heart condition or for a blood clot in the legs or lungs or simply before or after orthopedic surgery.

Aspirin and Clopidogrel (Plavix) are NOT blood thinners in the classic definition that doctors use. The most commonly used blood thinner has been Coumadin ( Warfarin ). However over the past few years, newer blood thinners have come out for medical use which have several advantages such as no blood testing being required to see if the blood is adequately thin. These newer anti-coagulants are called “NOACS” or Novel Oral Anti-coagulants”.

We discuss more on these on –
http://www.vascular.ae/educational-brochures

Comparison of oral anticoagulants

Property Warfarin Rivaroxaban Dabigatran etexilate
Anticoagulant action Reduced synthesis of functional clotting factors II, VII, IX, and X. Direct competitive reversible inhibition of activated factor X Direct competitive reversible inhibition of thrombin
Prodrug No No Yes
Bioavailability Almost 100% 80% 6.5%
Onset of anticoagulant action 36-72 hours Within 30 minutes.Tmax 2.5-4 hours Within 30 minutes.Tmax 0.5-2 hours
Duration of anticoagulant action 48-96 hours 24 hours 24-36 hours
Elimination half-life (anticoagulant activity) 20-60 hours G5-9 hours in young adults 11-13 hours in older adults 7-9 hours in young adults 12-14 hours in older adults
Predictable pharmacokinetics No Yes Yes
Interactions with diet or alcohol Yes, clinically significant Low potential Low potential
Drug interactions Numerous clinically significant interactions Potent cytochrome P450 3A4 and P-glycoprotein inhibitors augment anticoagulant effect (e.g. ketoconazole, clarithromycin, ritonavir) Proton pump inhibitors reduce absorption Possible interactions with P-glycoprotein inhibitors and inducers
Dosing and dose adjustments Dose individualized for each patient, requires frequent INR monitoring and adjustment Fixed according to clinical indication Fixed according to clinical indication
Monitoring INR every 1-2 weeks No routine monitoring required No routine monitoring required
Use in liver failure Contraindicated or caution advised Contraindicated as hepatic metabolism Possibly safe as no hepatic metabolism or caution advised
Use in severe renal impairment No dose adjustment required Increased drug exposure and elimination half-life in renal impairment. Safety and dosing not yet established. Contraindicated in severe renal impairment. Increased drug exposure and elimination half-life in renal impairment. Safety and dosing not yet established. Contraindicated in severe renal impairment
Use in pregnancy Category D Teratogenic in first trimester Contraindicated as safety not established (excluded from clinical trials) Contraindicated as safety not established (excluded from clinical trials)
Reversibility after cessation Several days, requires synthesis of clotting factors 24 hours, dependent on plasma concentration and elimination half-life 24-36 hours, dependent on plasma concentration and elimination half-life
Antidote Immediate reversal with plasma or factor concentrate. Reversal within hours with vitamin K None available None available
INR  international normalised ratio
Tmax  time to maximun concentration

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Comparison of oral anticoagulants