The Japanese Ministry of Health, Labor, and Welfare, the equivalent of the U.S. FDA, approved Bristol-Myers Squibb (BMY 0.34%) and Pfizer's (PFE 0.55%) Eliquis for the prevention of strokes and blood clots in patients with nonvalvular atrial fibrillation, a type of irregular heartbeat.

Eliquis reduced the risk of stroke, major bleeding, and all causes of death compared with warfarin. Eliquis' competitor is available as a generic but is difficult for doctors to dose properly because the dosage requirements vary among patients and there's a small range in which the drug works -- too little and it doesn't work; too much and the drug causes bleeding .

This is the third approval for Eliquis in nonvalvular atrial fibrillation within six weeks; the drug was recently approved in the EU and Canada. In the U.S., the FDA issued a Complete Response Letter in June, requesting additional data and verification from ARISTOTLE, the pivotal clinical trial supporting Eliquis' use in atrial fibrillation. The companies have already reapplied, and the FDA has set a goal to respond on or before March 17, 2013.