* Brilinta okayed for use beyond 12 months at new 60 mg dose
* Company says move supports "strong and consistent growth"
* AstraZeneca targeting Brilinta sales of $3.5 bln by 2023 (Adds executive and analyst comments on Brilinta growth)
By Bill Berkrot and Ben Hirschler
Sept 4 (Reuters) - U.S. regulators have approved a new dose of AstraZeneca's blood thinner Brilinta for longer-term use in patients with a history of heart attacks, boosting prospects for a drug the company thinks will eventually sell $3.5 billion a year.
The green light from the U.S. Food and Drug Administration (FDA), announced late on Thursday, could theoretically more than double the number of people eligible for the medicine.
In practice, while the new label will certainly help, long-duration therapy may be reserved for patients with particularly high heart risks and little danger of bleeding complications, said Deutsche Bank analyst Richard Parkes.
The FDA approved Brilinta at a new 60 milligram (mg) dose to be taken with aspirin beyond a year after a heart attack. The drug, used to prevent blood clots that can cause heart attacks, strokes and deaths, had previously been approved at a higher dose just for use during the 12 months after a heart attack.
The FDA move comes a week after European heart experts endorsed the potential use of Brilinta and similar blood clot preventers beyond a year.
The expanded approval suggests patients could be taking Brilinta for considerably longer than now and the FDA did not set any limit on the duration of treatment.
Tom Keith-Roach, vice president for Brilinta at AstraZeneca, told Reuters the FDA endorsement would shift thinking among heart doctors and expand the market, as clinical practice moves increasingly towards longer-term drug use.
Only about a quarter of acute coronary patients in the United States who start on Brilinta, or rival blood-thinners, remain on treatment for 12 months. In Europe, more patients do receive therapy for a year but very few are treated beyond that.
"We're not going to see fireworks but this will support really strong and consistent growth over time. I've got a nice straight line that goes from our current reported sales to my $3.5 billion," Keith-Roach said.
Selling more Brilinta is a high priority for the British drugmaker. During a takeover battle with Pfizer last year, it forecast annual sales of the drug could reach $3.5 billion by 2023.
Consensus forecasts currently point to sales of $1.7 billion by 2020, according to Thomson Reuters Cortellis, suggesting considerable upside if AstraZeneca hits its target. Brilinta sales rose 23 percent to $144 million in the second quarter.
Under the new FDA recommendations, patients with a history of heart attacks can be treated with 60 mg of Brilinta twice daily along with a daily maintenance dose of aspirin of 75 to 100 mg, beyond the first year's treatment.
AstraZeneca also has clinical trial programmes under way to expand the use of Brilinta in stroke, peripheral arterial disease and diabetes. (Reporting by Bill Berkrot in New York, Samantha Kareen Nair in Bengaluru and Ben Hirschler in London; editing by Bernard Orr and David Clarke)