As increasing numbers of adverse events involving the blood-thinner Pradaxa were reported in 2011, one of Boehringer-Ingelheim’s  (BI) competitors, Bayer AG (yes, of the aspirin fame) came up with its own medication, Xarelto. The move forced Boehringer-Ingelheim to cut the price it charged the U.K.’s National Health Service by 13 percent. (This price cut of course does not affect U.S. consumers, who continue to be held hostage to a profit-driven system – “Obamneycare” notwithstanding. Their costs still run between $6 and $9 a day, while Britons get the same medications for between $1.35 and $1.60 USD.)

One of the problems that Xarelto has been running into however is the fact that its side effects are still relatively unknown.

The clinical name for Xarelto is rivaroxaban. It prevents clotting by inhibiting the action of a  biochemical substance produced in the liver, known as “Factor X.”  It binds to another substance, called “Factor V” in a process that requires Vitamin K. The end result is the production of  thrombin –  the substance that actually causes blood clotting.

Pradaxa (dabigatran) inhibits the action of thrombin – while Xarelto prevents it from forming in the first place.  Coumadin (warafarin), which has long been the first-line treatment for patients in danger of stroke and coronary events due to clots, acts on Vitamin K itself.

This is why hemorrhaging caused by Coumadin can be readily treated by dosing the patient with Vitamin K, while hemorrhaging caused by Pradaxa is usually fatal (the only treatment at present is emergency dialysis in order to rid the system of the drug).

An “indirect comparison” between Pradaxa and Xarelto showed that at the highest doses, Pradaxa did a better job of preventing strokes than its competitor. At lower doses however, there was not a great deal of difference. A drug currently undergoing clinical trials in the U.S., apixaban, appears to lower the risk of hemorrhaging by as much as 26 percent as compared to Pradaxa at higher doses – but again, there was little difference at lower doses.  Apixaban is similar to Xarelto in that it works on Factor X. Interestingly, the comparison suggests that patients given apixaban are 36% less likely to experience hemorrhaging than those medicated with Xarelto, when administered higher doses. This drug, is already sold in Europe under the brand name Eliquis,  is eliminated from the body by the liver rather than the kidneys, as is the case with the other two drugs. It therefore may be a better choice for older patients, or those suffering from reduced kidney function due to disease.

Despite the fact that the new medications are easier to prescribe and have far fewer interactions (thus requiring less monitoring),  the vast majority of doctors are still prescribing warfarin – by fifteen to one over Pradaxa, and over 250 to one over Xarelto. One reason that doctors continue to shy away from Xarelto is because there is still much that is unknown about its side effects. Other reasons that most doctors continue to prescribe warfarin: hemorrhaging due to this proven medication is easier to control, and because it is available in generic form, the cost of warfarin is only about $16.30 per month – compared to Pradaxa’s price tag of  $250 per month.

Sources

Hardy, Scott. “Doctors Discuss Pradaxa, Eliquis & Xarelto Side Effects. The Future of Blood Thinning & Anti-Coagulant Drugs.” Top Class Actions, 15 June 2012. Available at topclassactions.com/lawsuit-settlements/prescription/1988-doctors-discuss-pradaxa-a-xarelto-side-effects .

Lip, Gregory Y.H. MD, et. al. “Comparison of New Oral Anticoagulant Drugs for Efficacy and Safety When Used for Stroke Prevention in Atrial Fibrillation.”  Journal of the American College of Cardiology, vol. 60 no. 8 (August 2012).

Pierson, Randsell. “Pradaxa And Xarelto: Top Heart Doctors Concerned Over New Blood Thinners.” Reuters via Huffington Post, 14 June 2012. Available at http://www.huffingtonpost.com/2012/06/14/pradaxa-xarelto-blood-thinner-doctors-heart_n_1595971.html .