Eliquis (apixaban) was approved Friday for reducing stroke risk in patients with nonvalvular atrial fibrillation, becoming the third oral anticoagulant to reach the US market.

Following several delays, the FDA gave the nod three months prior to the drug’s expected approval date, clearing the 5-mg dose for use twice daily (a 2.5-mg pill was also approved). It follows regulatory OKs in Europe, Canada and Japan. Co-marketers Bristol-Myers Squibb and Pfizer have been counting on the launch to help replace revenues from blockbusters that went over the patent cliff, most notably Lipitor for Pfizer in November 2011 and Plavix for BMS last May.

Analysts expect the new tablet will come to dominate what could be a $10-billion warfarin-replacement market. “Eliquis should be the preferred choice for stroke prevention in atrial fibrillation (SPAF), but being third-to-market means the launch will take time,” wrote Leerink Swann’s Seamus Fernandez in an investor note this week. Fernandez expects a “relatively slow initial launch that picks up over time.” 

The agent may be well-positioned to eventually take the lead thanks to clinical results that showed safety similar to aspirin. Data for a fourth blood thinner in development, Daiichi-Sankyo’s edoxaban, are expected in 2013. (Click here to read MM&M’s January 2013 feature, Therapeutic Focus: Cardiovascular, which includes the latest revenue forecasts and an analysis of how the new blood thinners compare, plus what else is emerging from the CV drug pipeline.)

Despite some safety issues, physicians say they have been prescribing the two previously approved oral blood thinners, Boehringer Ingelheim’s Pradaxa (dabigatran) and Bayer’s/Johnson & Johnson’s Xarelto (rivaroxaban), to maintain anticoagulation levels among patients who have problems complying with Coumadin therapy, which is notorious for requiring regular monitoring to ensure patients stay within accepted levels.

“I think the introduction of a third alternative for the vitamin-K antagonist warfarin, or Coumadin, will increase the likelihood patients will be treated with one of these products,” said Randall Zusman, MD, associate professor of medicine at Harvard Medical School and director of the division of hypertension at Mass General Hospital’s Institute for Heart, Vascular and Stroke Care.

Like Xarelto, Eliquis has a black-box warning regarding discontinuation of therapy. “With rare exception, these drugs have been very well tolerated,” added Zusman.

One physician says the pharma industry could make it easier for the medical community to sort out which therapy is best. “Without head-to-head comparison trials (which are unlikely to be undertaken by industry sponsors), it is impossible to adjudicate which [oral anticoagulant] is the preferred one!” said Sanjay Kaul, MD, an attending cardiologist at the Cedars-Sinai Medical Center in Los Angeles and a professor of medicine at UCLA’s Geffen School of Medicine, in an e-mail.

Market inertia with warfarin, available as a cheap generic, may also affect Eliquis’ trajectory. The new drug has a wholesale price of $8.35 per day, which is similar to Pradaxa and just above Xarelto.

J&J has yet to report sales figures for Xarelto. In the first nine months of 2012, partner Bayer reported Xarelto ex-US sales of about $235 million. Pradaxa had $617 million in global sales for the first six months of the year, according to BI.