* Reviewers back 150 mg dose of Pradaxa, not 110 mg
* Say superiority claim over warfarin should not be granted
* FDA panel to review new oral anticoagulant on Sept 20
(Adds details, background on market size)
LONDON, Sept 16 (Reuters) - Boehringer Ingelheim's new anticoagulant pill Pradaxa should be approved in the higher of two suggested doses for the prevention of strokes in people with irregular heartbeats, U.S. drug reviewers said on Thursday.
But Food and Drug Administration (FDA) staff said the unlisted German company's drug -- the most advanced of a number of clot preventers in late-stage development -- should not be awarded a superiority claim over the older medicine warfarin.
The reviewers presented an in-depth analysis of the product in documents published on the agency's website ahead of an FDA advisory panel that will review Pradaxa on Sept. 20.
The analysis said Pradaxa, or dabigatran, should be approved for use in patients with atrial fibrillation at the 150 milligram (mg) dose but not 110 mg.
Pradaxa is vying with Bayer (BAYGn.DE) and Johnson & Johnson's (JNJ.N) Xarelto, as well as Bristol-Myers Squibb (BMY.N) and Pfizer's (PFE.N) apixaban, to displace the old, problematic heart drug warfarin.
Industry analysts believe the warfarin replacement market could be worth more than $10 billion a year and possibly as much as $20 billion. Bayer Chief Executive Werner Wenning this week put the market opportunity at $12 billion to $15 billion. (Reporting by Ben Hirschler and Ludwig Burger; Editing by Kate Kelland)