GlaxoSmithKline to seek approval for 20 new medicines by 2020

Sales fell from about $5.2 billion in the first nine months of 2014 to about $4.1 billion in 2015's first nine months, and newer respiratory drugs aren't picking up the slack.

The company envisages starting the clinical trials a.k.a late-stage patient testing in the next two years on about 20 new drugs or new uses for existing ones. And it could start mid-stage patient testing on about 30 others.

Meanwhile, generic competition to Advair looms, other big drugs already have lost patent protection - and sales to cheaper generics - and Glaxo's stock price keeps falling. Shares traded in the U.S. are down 24 percent over the past 20 months, including another 1.5 percent drop Tuesday. Those all have been putting pressure on CEO Andrew Witty to produce better results or face an ouster.

"We need to make sure we have a company that is vibrant and in growth post-Advair," Witty, GSK's chief executive officer since 2008, told analysts and journalists during a presentation in New York.

The company has been pruning its research programs, cutting jobs and reducing other costs under a restructuring begun last year, an attempt to counter declining revenue and free up more money for research.

On Tuesday, GlaxoSmithKline presented details on 40 experimental medicines in the company's six core areas: HIV and infectious diseases, respiratory disorders, rare diseases, vaccines, cancer and the hot new category of cancer medicines that work by harnessing the immune system to better fight tumors.

"We all know not all of these assets will make it," Witty said, adding that Glaxo had an industry-leading 14 new drugs approved from 2010 through 2014. Those included a pandemic flu vaccine, Tivicay for HIV, and respiratory treatments Breo and Anoro.