Xarelto (rivaroxaban) is one of the newest anticoagulants – more commonly known as blood thinners. The drug is an oral medication developed by Bayer and Johnson & Johnson’s New Jersey-based unit, Janssen Pharmaceuticals. Blood thinners are used to prevent the onset of dangerous blood clots that can obstruct the blood flow to the vital organs. Unlike older anticoagulants that require doctors to prescribe specific doses for each individual, Xarelto belongs to a new type of oral anticoagulant that is prescribed in one uniform dose.
The Food and Drug Administration (FDA) approved Xarelto in July 2011 for use in patients who have had knee or hip replacement surgery to reduce the risk of blood clots, deep vein thrombosis (DVT) and pulmonary embolism (PE). In November 2011, the FDA expanded the approval of Xarelto for use in reducing the risk of stroke in people with AF. Then, in 2012, following a fast-track regulatory review, the FDA approved the drug for general treatment of DVT and PE, and reducing the risk of recurrent DVT and PE.
Another better-known oral anticoagulant is the drug Pradaxa (dabigatran etexilate), manufactured by Bayer’s competitor, Boehringer-Ingelheim. Xarelto and Pradaxa are similar, but they work in different ways. Xarelto inhibits a protein involved in the coagulation process called Factor Xa, which interrupts the blood-clotting process and prevents another protein, thrombin, from forming. Pradaxa directly inhibits thrombin from forming.
The current market for anticoagulants is estimated to be worth $10 billion, and many companies are developing newer drugs to get a piece of this market share. Previously, warfarin (Coumadin, Jantoven) was the industry standard anticoagulant. Because warfarin requires changes in diet and lifestyle, regular checkups, and has a risk of brain hemorrhage, drug companies developed and marketed oral medicines like Xarelto and Pradaxa as safer, more convenient alternatives. These drugs do not require frequent doctor checkups and have a uniform, “one-size-fits-all” dose.
Although newer anticoagulants like Xarelto and Pradaxa are helpful to numerous patients, they are more costly than warfarin. Xarelto costs about $3,000 a year compared with $200 for warfarin. They can also have some very dangerous side effects that may lead to lawsuits.
Xarelto Uses and Clinical Studies
Xarelto’s original FDA-approved use was as a blood thinner for patients recovering from knee or hip replacement surgery. In the RECORD study, a Phase III clinical trial of more than 9,500 participants, researchers found that Xarelto was more effective than another blood thinner, enoxaparin (Levenox), in reducing incidence of blood clots in the legs following hip or knee replacement surgery.
Xarelto is also used for preventing strokes in people with atrial fibrillation (AF). AF affects about 3 million Americans, and it is projected that 12 million people in the United States will be diagnosed with AF by 2020, so it is expected that newer anticoagulants such as Xarelto will become more popular.
In 2011, the New England Journal of Medicine published the results of a study that compared Xarelto to warfarin in patients with AF. The study, known as the ROCKET AF study, examined more than 14,000 patients in a double-blind test. The study showed that patients on Xarelto had less risk of suffering from bleeding in the brain when compared with warfarin, but the risk of overall bleeding was the same as warfarin. Bayer and Johnson & Johnson asked the FDA to approve a claim that the drug was superior to warfarin in stroke prevention, but the agency denied the request stating that clinical evidence only proved that Xarelto was just as effective as warfarin.
Side Effects of Xarelto
One of the most severe side effects of Xarelto is uncontrolled bleeding. When bleeding occurs near a major organ, such as the brain, lungs or kidneys, blood flow to that organ is interrupted, causing it to lose some or all of its functionality. Also, pools of blood may form within the body and can cause other severe health risks. Because Xarelto prevents clotting, the hemorrhaging will continue until the drug is flushed out of the system.
Like Pradaxa, Xarelto has no known antidote for uncontrolled bleeding, while warfarin does. The drug’s manufacturers have yet to release information for doctors on how to treat uncontrolled bleeding.
|Some other side effects associated with Xarelto and other blood thinners include:|
|Abdominal bleeding||Abnormal liver function|
|Brain hemorrhage||Reduced platelet levels|
Doctors recommend that patients with liver or kidney problems, as well as those who are pregnant, breastfeeding or planning to breastfeed should not take Xarelto. In addition, people who are on Xarelto and have spinal injections, epidurals or surgery have increased risk of forming a blood clot in the spine that can cause paralysis. The risk of spinal clotting is increased for people who take NSAIDS like aspirin and ibuprofen (Advil) or people who have a history of spinal problems and surgery.
Xarelto also has an extensive list of drug interactions that can cause serious problems, including increased bleeding risk.
|Drugs that may adversely react with Xarelto include:|
|Carbamazepine (Carbatrol, Equetro, Tegretol, Tegretol-XR, Teril, Epitol)||Indinavir (Crixivan)|
|Itraconazole (Onmel, Sporanox)||Ketoconazole (Nizoral)|
|Lopinavir/ritonavir (Kaletra)||Phenobarbital (Solfoton)|
|Phenytoin (Dilantin-125, Dilantin)||Rifampin (Rifater, Rifamate, Rimactane, Rifadin)|
|Ritonavir (Norvir)||St. John’s wort (Hypericum perforatum)|
In a Phase III study intended to examine the drug’s safety, 73 percent of the 16,041 participants who took at least one dose of Xarelto experienced side effects. Some of the most prominent serious side effects were anemia and bleeding events. People who took a higher dose were more likely to suffer from bleeding.
|Participants of the study also suffered from:|
|Hemorrhaging in the eye||Rapid heartbeat|
|Low blood pressure||Bruising|
|Nose bleeds||Gastrointestinal and Urogenital bleeding|
In addition to these side effects and drug interactions, the FDA released a warning that patients who suddenly stop taking Xarelto can be at increased risk for developing blood clots.
Xarelto’s predecessor, Pradaxa, has already led to a number of lawsuits filed against its manufacturer because of complications such as excessive bleeding and death. Xarelto is similar to Pradaxa, and there is a danger that it may cause similar complications and result in lawsuits. Another reason for concern is that the drug was fast-tracked for approval by the FDA – meaning that there may be a chance that the complete safety profile of the drug may still be unknown.