Sunday, June 08, 2008


At the just concluded annual scientific meeting of the European Federation of National Orthopedic Associations, the Canadian workers from McMaster University, Hamilton, Ontario presented the findings of RECORD4, a study comparing the blood thinning effects of a new blood thinner, named Rivaroxaban 10mg orally., against subcutaneous low molecular weight enoxaparin 30mg BD, in the prevention of deepveinous thrombosis following knee replacement surgery. They found that oral rivaroxaban was good as SC enoxaparin, and was just as safe. It also does not require frequent blood monitoring. Now we have another oral anti-coagulant. For so long, we only had warfarin as an oral anticoagulant. You may remember that warfarin, is a coumadine derivative and is essentially rat poison. It thins the blood by interfering with the production of factor 5,7,10 in the liver. These factors form part of the extrinsic anticoagulation cascade. Warfarin was effective except that it required frequent blood monitoring of the PT-INR, as warfarin has a low therapeutic index ( the effective therapeutic dose is rather close to the toxic dose ). Also warfarin has interactiosn with many drugs and even frequently consumed food like garlic, ginger and good old Chinese ginseng, making it a very fussy drug. Bleeding has proven to be a very common problem with the use of warfarin and some of these bleeding, like upper GIT bleed of intracranial bleed, could be life-threatening. The search for a warfarin alternative has been going on for awhile and there had been many candidates, but non-as suitable as rivaroxaban. The previous drugs tried were effective but had unacceptable side-effects. Well, we know that Rivaroxaban can thin the blood to prevent deep vein thrombosis following knee replacement surgery, but can it also prevent strokes in patients with atrial fibrillation and also is it effective in preventing acute coronary syndrome in coronary artery disease. Can it be used to thin the blood in patients with valvular replacement. Well, studies are being done to establish all if these indications and we await the results. For a start, rivaroxaban looks okay. This product is owned by Johnson and Johnson and also bayer. I understand that they are filing for FDA approval. In the US, it will probably be marketed by JnJ, and out of the US, it will be marketed by Bayer Healthcare. We wait expectantly for it to reach Malaysia. And of course, there is the issue of cost. I do not think that it will be cheap, certainly not as cheap as warfarin. Warfarin is literally dirt-cheap.

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