Pfizer is planning to hold on to every Lipitor prescription it can as the company’s biggest drug – which is manufactured in Cork – faces a first wave of US generic competition this month.

Chief executive Ian Read described his determination to at least temporarily protect the $10 billion (€7.3 billion) a year cholesterol fighter from the steep sales declines that large medicines typically suffer when they lose marketing exclusivity in the United States.

“Whether this is possible in a market like the US is very unpredictable,” Mr Read said.

Lipitor’s patent protection expires on November 30th, when new versions of the drug are expected to be sold by Ranbaxy Laboratories Ltd and Watson Pharmaceuticals Inc.

Pfizer earned $3.74 billion, or 48 cents a share in the third quarter, including a $1.3 billion after-tax gain on the recent sale of its Capsugel business.

Company revenue rose 7 per cent to $17.19 billion.