Ireland’s tax regime may again face the international spotlight, at an uncomfortable time for the country, after two of the world’s pharmaceutical giants yesterday confirmed they are in talks over a mega billion dollar merger that appears to be driven by Irish tax considerations.

US-based Mylan yesterday offered to buy fellow drugmaker Perrigo whose headquarters are in Dublin for $28.9bn (€26.73bn), a deal that would create a powerhouse for generic medicine.

A Dublin-headquartered pharmaceutical giant has completed its takeover of a US rival for $66bn (€62bn).

Actavis, which began as a small New Jersey-based generic pill-maker called Watson Pharma, will take the name Allergan after agreeing to buy its new namesake in the drug industry’s largest deal of last year.

Drugs giant AstraZeneca is to boost its portfolio with the acquisition of a branded respiratory drug business for up to US $700m (€613m).

US investors remained in a record-setting mood, edging the Dow Jones industrial average and Standard & Poor’s 500 index to their latest all-time highs.

Actavis plc agreed to pay about $66bn (€53bn) for Allergan, a deal that creates a new top 10 drugmaker and ends Valeant Pharmaceuticals International’s attempt at a hostile takeover of the maker of Botox.

Pre-tax profits at the main Irish subsidiary of US-owned pharmaceutical firm, Forest Laboratories last year increased more than four-fold to $426.49m (€341m).

Actavis plc is being sued by New York attorney general Eric Schneiderman over claims it is trying to block generic competition by swapping versions of its Namenda Alzheimer’s drug, a move he says is part of a growing trend in the pharmaceutical industry to maintain high prices.

AstraZeneca’s stock has been rising for two weeks on growing expectations the British pharmaceutical firm will re-engage in merger negotiations with Pfizer after the partial expiration of a cooling-off period.

A spate of takeover activity in the pharmaceutical sector pushed Irish-related acquisition values to a 20-year high in the first half of 2014 and saw the country account for nearly 18% of European merger activity, in value terms.

Dublin-based firm Actavis, one of the world’s largest generic-drugs makers by market value, has agreed to buy Forest Laboratories for about $25bn (€18bn).

Allergan chief executive David Pyott said he probably won’t follow other drugmakers in making an acquisition in Ireland as a way to lower the company’s corporate taxes.

JAZZ Pharmaceut-icals just got more alluring as a takeover target after adding to its suite of medicines for rare diseases.

There was a significant decline in Irish-related merger, acquisition and equity investment activity during the first half of this year, with transactions nearly halving on the same period last year, new data shows.

Generic drug maker Actavis has agreed to acquire Dublin headquartered Warner Chilcott for about $5bn (€3.9bn) excluding net debt in a deal to expand in women’s health and urology.