Pfizer is highly unlikely to pursue any mega-mergers but will continue to look at bolt-on acquisitions and more research alliances, according to chief executive Ian Read.

Speaking at the JP Morgan Global Healthcare Conference in San Francisco, Mr Read said "I'm very disinclined to be looking at the possibility of another mega-acquisition". This marks a major switch in strategy for the firm which has established itself as the world's largest drugmaker over the last decade after buying Wyeth (in 2009), Pharmacia (in 2003) and Warner-Lambert (in 2000).

He said "we're only going to do bolt-on acquisitions or licensing deals that make sense financially," adding that “you never say never, but we have all the science we need and we have the geographic breadth". He also highlighted five drugs that will drive growth in the near term - the pneumococcal vaccine Prevnar 13, the lung cancer drug Xalkori (crizotinib), axitinib for advanced kidney cancer, tofacitinib for rheumatoid arthritis and the anti-clotting drug Eliquis (apixaban), partnered with Bristol-Myers Squibb.

In terms of prioritising the R&D portfolio, Mr Read noted that the company has terminated over 90 pre-proof-of-concept programmes. Pfizer has been creating "a smaller, more flexible cost base", he said and its chief scientific officers are now "operating with increased cost transparency and accountability for a greater proportion of the total spend".

When asked how plans to spin off or sell Pfizer's animal health and nutrition businesses are progressing, the CEO said “it is on track and we are happy with the way it is going". Mr Read claimed that “they are great businesses, but they have a value that can be better explored outside Pfizer".