By Zeba Siddiqui

MUMBAI (Reuters) - Generic drugmaker Cipla (CIPL.NS) expects sales from its respiratory portfolio to more than double by 2020 and remains on track to launch its potentially lucrative inhaler in Britain, its chief executive said.

More than a decade after it made headlines globally for offering to make AIDS drugs costing less than $1 a day, the company that was a pioneer in India's development as a force in generics is now working on producing cheaper medicines for respiratory diseases.

The specialised production capabilities required to copy such drugs serve to limit competition and have persuaded Indian companies such as Dr Reddy's Laboratories (DRRY.NS), Lupin (LUPN.NS) and Cipla to build expertise in the segment.

Most large generic drugmakers in India's $15 billion pharmaceutical industry are focusing on developing niche drugs that are difficult to make as the market for easy-to-copy generics becomes increasingly competitive and less lucrative.

Seroflo, a generic version of GlaxoSmithKline's (GSK.L) Advair inhaler, is one of Cipla's biggest bets in the respiratory space. Advair, used to treat asthma and chronic obstructive pulmonary, was among the world's 10 best-selling drugs last year.

Cipla, India's fourth-largest drugmaker by revenue, has launched its product in seven countries so far and was hoping to be the first to launch the generic in a British market worth $400 million a year.

But in what industry analysts called "a big setback" to the company last week, larger rival Mylan & Co (MYL.O) beat it to the punch with the British launch of its own Advair generic.

Cipla CEO Subhanu Saxena said the company had not revised its internal sales forecast for Seroflo.

"It would have been nice to be first, obviously. But we are still pretty much in line with our own timelines," Saxena, who joined Cipla from Switzerland's Novartis (NOVN.VX) in 2012, told Reuters. Cipla said last July that it planned to roll out Seroflo in the UK in 12 to 18 months.

GEOGRAPHIC BALANCE

Seroflo is part of Cipla's push towards building its business in developed markets.

Though keen to reduce reliance on emerging markets that account for about 80 percent of the company's sales, Saxena is wary of going too far the other way.

"I don't want, like our competitors, to have 50 or 60 percent of our business dependent on the U.S. With geographic risk, I wouldn't want that to happen," Saxena said.

Cipla expects the United States to bring in a fifth of total sales by 2020, against 8 percent now.

The U.S. growth plan could include acquisitions, Saxena said, adding that it would not overpay.

"We have a lot in our own hands, so we don't have to pay crazy prices," he said.

With sales in India, Cipla's largest market, hit over the past year by government price controls on drugs, the company is also planning to enter Latin America and Eastern Europe to tap growing demand for generics, Saxena added.

Cipla has launched operations in countries such as Iran and Yemen but now faces increased competition in emerging markets from India's largest drugmaker Sun Pharmaceutical Industries (SUN.NS), analysts say.

Sun Pharmaceutical recently completed a deal to buy domestic company Ranbaxy Laboratories, strengthening its offering in India and other emerging markets.

Cipla, however, is ready to take up the gauntlet, Saxena said.

"The U.S. is always going to be big, and we will be an important player ... but I can see a lot of growth outside that area," he said. "In India itself, we are just scratching the surface."

(Additional reporting by Sumeet Chatterjee; Editing by Muralikumar Anantharaman and David Goodman)