Clot formation in the veins
of the legs, a condition called venous thrombosis can have serious
consequences. The clots can travel to vital organs like the heart, lungs and
brain, in the form of emboli, obstructing the flow of blood in them.
Treatment of venous
thromboembolism involves the use of drugs belonging to the group anticoagulants,
which prevent the blood from clotting. Initial treatment involves the use of
injected anticoagulants like heparin and low molecular weight heparin.
Following this, the patient is put on oral drugs like warfarin to prevent
further formation of venous clots.
The use of warfarin is not
entirely easy. The patient has to be regularly monitored to make sure that the
warfarin levels are maintained and the patient does not suffer from
complications of excessive bleeding. In addition, warfarin should be used carefully
if the patient is on other medications as well.
Two new classes of drugs
have been recently introduced to overcome the disadvantages of warfarin. These
are the direct thrombin inhibitors and factor Xa inhibitors. A study compared
these drugs relative to the older medications in the treatment of venous
thromboembolism from published data. The newer drugs studied included
rivaroxaban, apixaban, dabigatran and ximelagatran (though ximelagatran has
been withdrawn from the market due to risk of liver damage, it was included in
The study found that the newer anticoagulants are similar to
warfarin in terms of risk of recurrence of venous thromboembolism and all cause
mortality. Though most new anticoagulants showed a lower risk of bleeding as a
side effect as compared to warfarin, the risk was significantly lower only with
Further studies are needed to establish this advantage of
rivaroxaban, according to the authors.
The study thus concluded
that most new anticoagulants are similar in efficacy and safety as compared to
warfarin, with possible reduced chances of bleeding. In addition, they seem to
be similarly effective among themselves. Further studies directly towards
comparing the different anticoagulants could help to establish an advantage of
some anticoagulants over the others.
1. Efficacy and safety of novel oral
anticoagulants for treatment of acute venous thromboembolism: direct and
adjusted indirect meta-analysis of randomised controlled trials; Benjamin Fox et
al; BMJ 2012