Turning around drugmaker AstraZeneca will be a long haul, with a strategy of revamping research and boosting acquisitions set to take up to four years to pay off, its chief executive said on Tuesday.

Speaking as the group unveiled the location for a new global headquarters and research center in Cambridge, England, Pascal Soriot said he was not expecting any short-term fixes for the group, which is struggling from falling sales as patents expire. "You've got to look at this over a horizon of three to four years, it is not a six-month horizon," he said in a telephone interview from Cambridge. "And it is not going to be a smooth journey. We will have ups and downs."

The company's new $500 million site on the southern outskirts of the university town, which will be purpose-built, is only set for completion in 2016. However, AstraZeneca plans to transfer some staff from its existing Alderley Park facility in northwest England before then, possibly as early as the end of 2013, using rented laboratories and offices. "We will have people based here potentially at the end of the year and we will start benefiting from the location," Soriot said.

Cambridge is a major center for life science research, which Soriot said could rival San Francisco and Boston, and he hopes to tap into that knowledge base by having his scientists working close to top academics and clinicians.

Targeted acquisitions in three key areas - cardiovascular and metabolic medicine, oncology, and respiratory and inflammatory drugs - are another important plank of Soriot's turnaround plan.

Despite urgings from some analysts, he has eschewed large-scale deals, preferring to focus instead on bolt-on acquisitions, often of private companies, such as last week's purchase of Pearl for up to $1.15 billion.

Britain's second-biggest drugmaker has suffered from a series of failures of experimental medicines that have weakened its pipeline, forcing it to go shopping for promising new drugs invented by smaller biotech companies. "We will keep looking at potential deals to keep building our pipeline," Soriot said. "You will see by the end of the year or early next year that our late-stage pipeline will look very different as a result of some of those acquisitions, but also with the acceleration of some of our Phase II projects that are moving into Phase III right now."

Among existing products, investors are focused on prospects for diabetes drug Onglyza, co-owned with Bristol-Myers Squibb, which may show a cardiovascular benefit in a clinical trial - an outcome that would give it a marketing edge.