![]() ![]() Prior to the introduction of direct factor Xa inhibitors, vitamin K antagonists such as warfarin were the only oral anticoagulants for over 60 years, and together with heparin have been the main blood thinners in use. Main article: Discovery and development of direct Xa inhibitors Antistasin, the first discovered naturally occurring direct Xa inhibitor Rivaroxaban, the first synthetic direct Xa inhibitor marketed as a drug Īlso in contrast to warfarin and phenprocoumon, direct factor Xa inhibitors do not require frequent monitoring of the prothrombin time (also called the INR) and dose adjustments. By contrast, warfarin and phenprocoumon are often paused up to a week before surgery, and low-molecular-weight heparins are used to "bridge" the therapy gap, typically for several weeks. This means it is often possible to pause them 12 to 48 hours before surgery and resume them shortly after the surgery. They have a rapid onset and offset of action. Pharmacology Mechanism of action Coagulation in vivo, shows final common pathway and where factor Xa actsĭirect factor Xa inhibitors block the enzyme called factor Xa, preventing the conversion of prothrombin to thrombin in the final common pathway of clot formation in veins and the heart. Compared to warfarin they have fewer interactions with other medications. The blood thinning effects can be reduced if used at the same time as rifampicin and phenytoin, and increased with fluconazole. The risk of bleeding is increased if used at the same time as other blood thinning drugs such as nonsteroidal anti-inflammatory drugs, antiplatelet drugs and heparin. Andexanet alfa, a specific antidote to reverse the anticoagulant activity of direct Xa inhibitors in the event of major bleeding, was approved by the FDA in 2018. Overdose Ī specialist may request a quantitative factor Xa assay in a situation of overdose. Other side effects may include stomach upset, dizziness, anemia or increased blood levels of liver enzymes. Compared to the risk of bleeding with warfarin use, direct factor Xa inhibitors have a higher risk of GI bleeding, but lower risk of bleeding in the brain. Side effects may include bleeding, most commonly from the nose, gastrointestinal tract (GI) or genitourinary system. The effects on a fetus or neonate are unknown, hence these drugs are not prescribed in pregnancy or breast feeding mothers. Contraindications ĭirect Xa inhibitors are contraindicated in people who are actively bleeding or who are at high risk of bleeding. Factors considered before deciding on whether warfarin or a DOAC or which direct factor Xa inhibitor is used, include: the presence or absence of valvular heart disease, state of kidney function, the risk of stroke and the risk of bleeding. ![]() ĭirect factor Xa inhibitors can be considered as an alternative to warfarin, particularly if a person is on several other medications that interact with warfarin, or if attending medical appointments and laboratory monitoring becomes difficult. They are commonly prescribed to treat and prevent blood clots in veins, prevent stroke and embolism in people with non-valvular atrial fibrillation (AF) who have other risk factors, and prevent blood clots after routine knee and hip replacement surgery. Medical use ĭirect factor Xa inhibitors include rivaroxaban, apixaban and edoxaban, and are types of direct oral anticoagulant, which are blood thinning drugs, one of the classes of antithrombotic drugs. Inhibit fibrin formation in the final common pathway of the coagulation cascadeĭirect factor Xa inhibitors ( xabans) are anticoagulants (blood thinning drugs), used to both treat and prevent blood clots in veins, and prevent stroke and embolism in people with atrial fibrillation (AF). Direct Xa inhibitor, novel oral anticoagulant ![]()
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