PHARMACEUTICAL companies around the world are poised to launch generic versions of Irish-made Viagra, following the expiration of Pfizer's patent in a number of European countries.

US medical giant Actavis and Israeli pharmaceutical company Teva released their own versions of the erectile dysfunction treatment yesterday after its patent ran out in 11 European countries, including Ireland and the UK.

Viagra, which has often been highlighted as one of the drugs that made Ireland an export champion, is the latest in a series of major drugs manufactured here to lose its patent.

Organic chemicals and pharmaceutical products accounted for nearly two-thirds of all Irish exports in the first half of 2011, but that figure has been falling ever since.

It was down to just a quarter in the first months of this year. Most of this decline is due to the expiry of patents on popular drugs, allowing competitors to offer cheaper generic versions.

Once-lucrative cholesterol medicine Lipitor, also made by Pfizer, lost its patent in most of the world in 2011.

Lipitor generated sales worth $9.5bn (€7.2bn) for the company in 2011 but these fell by nearly two-thirds the following year, meaning overall revenues at the multinational were down by a tenth in 2012.

Other Irish-made drugs that have gone off patent in the past few years include Eli Lilly's schizophrenia medicine Zyprexa and Merck's Singulair asthma treatment.

Until recently, Lipitor was made at Pfizer's plant in Little Ireland in Cork, but last month the company announced the closure of that facility in the face of plummeting sales.

It has also closed another Cork site and sold its Dun Laoghaire operation to Amgen in recent years.

It makes Viagra at its remaining Cork plant in Ringaskiddy.

The company, the world's biggest drug manufacturer, has cut more than 1,000 Irish jobs in the past few years but is still one of the country's biggest employers, with 3,200 staff in Ireland.

STRATEGIC

It said yesterday that Ireland "remains a key strategic location" despite the loss of the Viagra patent, and that four new drugs, treating cancer, osteoporosis and arthritis, would be manufactured for sale globally from this country.

It said Viagra would remain important because "patients will want to have ongoing access to a Pfizer medicine that they already know and trust".

It will adjust to the loss of the patent in certain markets by lowering the price of Viagra in those countries, in an effort to retain brand loyalty.

Here, the medicine will cost 70pc less for the remainder of 2013 and will return to half price at the beginning of next year.

It is still protected by a patent in the US, which will run until October 2019.