With EU regulatory approval in the bag and US regulatory scrutiny expected to clear in the coming weeks, the 55bn AbbVie and Allergan merger should start in earnest in February or March.
AbbVie, although headquartered in the US, has manufacturing sites in Cork and Sligo, while Allergan has its headquarters in Dublin and main manufacturing base in Westport.
However, the newly merged company will have its headquarters in Chicago, adding to a trend, in recent years, of dilution of pharmaceutical company headquarters in Ireland.
Both companies will face the arduous task of meshing into a single firm, with mandatory disposal of some units to comply with the EU regulatory approval.
But that process could take some time to execute, with potentially serious consequences for the Irish manufacturing and research facilities, particularly for the smaller partner, Allergan.
AbbVie, in an early announcement, stated that its post-merger strategy is to restructure Allergans cosmetic portfolio into a stand-alone cosmetics unit, to be called Allergan Aesthetics.
Its treatments include frown-line smoothing, eyelash lengthening, and double-chin removal.
This Botox business unit had shown lethargic growth in the recent past and AbbVie hopes the spin-off will address the fears of its negative impact on the rest of the business.
The strategy would move the cosmetic-wrinkle treatment Botox product to the Allergan Aesthetics unit, while the higher-margin, speciality eye care Botox products would be merged with the existing AbbVie structure, which includes gastrointestinal disease and central nervous system products.
This could be devastating for the Allergan facilities in Westport and Dublin, leaving them open to downsizing and eventual sell-off.
Much will depend on where the Botox eye-product manufacturing facility is located.
AbbVie is focused on squeezing cost reductions out of the merger and has stated that it expects to reap at least 1.76bn in annual cost-savings in the three years after the acquisition, in an effort to substantially pay down its cost-of-acquisition debts by the end of 2021.
However, it is early days in the merger strategy and Allergans medical- aesthetics business, as a stand-alone unit with its own research-and-development team, may develop new products and expand.
But that demerging, and the new unit set-up process, could take some time to execute and leave opportunities for competitors such as Evolus, maker of Botox competitor, Jeuveau, to disrupt the market leaders grip on the multi-billion cosmetics aesthetics market.
There is also the potentially very damaging regulatory case in the US, where the International Trade Commission judge, last August, ordered Allergan to turn over details of its Irish Botox cosmetic manufacturing process to Evolus.
The request has been robustly refuted, with strong legal justification for the protection of its trade secrets.
The final arbitration decision is due over the coming months, which could give Evolus a significant technical advantage, or a substantial financial settlement.
Either way, AbbVie, undoubtedly, have factored this scenario into their decision to separate out the Allergan Botox cosmetics division.
AbbVie was spun off by US firm, Abbott Laboratories, in 2013, and has been on the acquisition trail ever since. It was blocked in a 48bn attempt to buy Shire pharmaceuticals in 2014, after Barack Obamas administration introduced rules to clamp down on overseas acquisitions driven by tax-avoidance.
Shire, which was founded in Basingstoke, England, but headquartered in Ireland, was subsequently acquired by Japans biggest pharmaceutical company, Takeda, for 53bn last year, with a further loss of the headquarters advantage in Ireland. 2020 Global Data Point.