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Thursday, October 30, 2003A new, easier-to-use blood thinner pill offers the first potential alternative in 50 years to warfarin, the standard treatment given to millions of people to prevent blood clots. The new drug has been tested in 17,000 patients for a number of uses and has been shown to work as well as -- or, in some cases, better than -- warfarin at preventing dangerous blood clots. It acts more quickly and does not require the frequent blood testing of warfarin, also known as Coumadin. The new drug is called Exanta, and it's the subject of two papers in this week's New England Journal of Medicine. One paper compares its effectiveness to Coumadin in preventing blood clots after total knee replacement. This is a use of Coumadin not often seen here in the States. Most American orthopedists use injectable low molecular weight heparin instead. (It has fewer side effects and doesn't need monitoring the way Coumadin does.) They found that 20.3 percent of patients receiving the higher dose of Exanta ended up with blood clots after surgery compared to 27.6 percent of those receiving Coumadin. Unfortunately, it wasn't any safer than Coumadin: Major bleeding occurred during treatment in six patients in each of the two ximelagatran [Exanta - ed.] groups and in five patients in the warfarin [Coumadin -ed] group. Additional major bleeding events occurred during follow-up in four patients in the lower-dose ximelagatran group and in one patient in the warfarin group. One bleeding complication was fatal; gastric-ulcer bleeding developed in a patient who had received two 36-mg doses of ximelagatran. The bleeding led to multiorgan-system failure and death on day 46. This patient had also received perioperative enoxaparin (as part of the anesthesia protocol) and diclofenac. Looks like low molecular weight heparin will continue to be the standard of care after knee replacement on these shores. The other study looked at Exanta's effectiveness in preventing recurrent blood clots in the legs. Normally, after someone has a blood clot in the leg for the first time, we put them on Coumadin for six months then stop it. The risk of bleeding from prolonged Coumadin use outweighs any benefits it confers in preventing future blood clots. In this study, people who had already completed their six month course of Coumadin were placed on Exanta for another eighteen months and compared to those who weren't: Data from 612 patients in the ximelagatran group and 611 in the placebo group were analyzed. The occurrence of the primary end point, symptomatic recurrent venous thromboembolism, was confirmed in 12 patients assigned to ximelagatran and 71 patients assigned to placebo (hazard ratio, 0.16; 95 percent confidence interval, 0.09 to 0.30; P<0.001). And side effects? They appear to be about the same as placebo: Death from any cause occurred in 6 patients in the ximelagatran group and 7 patients in the placebo group, and bleeding occurred in 134 patients and 111 patients, respectively (hazard ratio, 1.19; 95 percent confidence interval, 0.93 to 1.53; P=0.17). The incidence of major hemorrhage was low (six events in the ximelagatran group and five in the placebo group), and none of these hemorrhages were fatal. Although it looks like liver enzymes will have to be monitored: The cumulative risk of a transient elevation of the alanine aminotransferase level to more than three times the upper limit of normal was 6.4 percent in the ximelagatran group, as compared with 1.2 percent in the placebo group (P<0.001). So, at this point in the research, it doesn't look like the new drug will replace Coumadin to treat blood clots, but it may be a drug that can be used indefinitely to prevent a recurrence. That is, if it turns out to be safe in the long term. Unfortunately, only time and use will determine that. posted by Sydney on 10/30/2003 09:23:00 AM 0 comments 0 Comments: |
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