There is concern for the future of up to 180 jobs at the pharmaceutical company Pfizer in Co Cork.

This follows a 19% drop in profits in the first quarter of 2012, due to falling global sales of its cholesterol drug Lipitor, which has come off patent in the US and in Europe.

Pfizer is one of the most successful and longest established multi-nationals operating in this country.

It has invested more than €5.5 billion in Ireland, and employs 4,000 people here.

But a number of its drugs have either come off patent or are about to do so. The company's cholesterol-lowering treatment Lipitor has been the best-selling drug in the world. But Lipitor's patent expired in the US last November and in Europe last month, hitting sales of the drug and the company's revenues.

The ending of patents on Lipitor and some of Pfizer's other drugs was expected to have an impact on its operations in this country. Those concerns have been renewed with reports that the company is planning to shed up to 180 jobs at Little Island and at Ringaskiddy in Co Cork.

A company spokeswoman said Pfizer does not comment on speculation, and any information would be shared first with its employees.

SIPTU is seeking clarification from Pfizer management on the issue, saying that the union was aware of the business review and that the company had given a commitment to speak with the workers directly once the review had been completed.