Some of the world’s biggest pharmaceuticals companies are likely to embark on a buying spree as imminent patent expiries combine with a greater willingness from biotechs to sell out.

The leading pharma companies are seeking to compensate for an estimated drop of more than $100bn in sales over the next five years on blockbusters such as Pfizer’s Lipitor, Wyeth’s Effexor, Merck’s Singulair and Eli Lilly’s Zyprexa.