Pfizer has finally managed to get enough shares to acquire pain specialist Icagen, at the end of yet another offer period.

The US giant says that just under 5.4 million shares have been tendered, bringing its total ownership of Icagen to 70.2%. It will now carry out a 'second-step'  merger as a result of which Icagen will become a wholly-owned subsidiary of Pfizer.

It has been quite a battle to complete the deal. In July, Pfizer agreed to acquire Icagen for $56 million, or $6 a share, and at the time it had a stake of around 11%. However, the deal was opposed by some shareholders who felt the offer was too low.

By the end of August, Pfizer's holding stood at around 49% but further extensions of the offer have now led to the company getting complete control.

The two firms have been partners since 2007 when they entered into a collaboration centred around compounds that modify three specific sodium ion channels and could be new treatments for pain and related disorders.