The plant produces billions of tablets each year but will close after Sanofi suffered a decline in European sales last year and generic competition to Plavix.
In a statement, Sanofi said the move had been made “in the context of an adverse economic climate and the challenging pharmaceutical market in Europe”.
It is understood the company is now beginning a 90-day consultation period with staff and unions.
Products including Plavix, Xatral and Epilem are currently manufactured at the site. Sanofi opened a new packaging plant at the site in 2009, bringing its investment to £100m in more than eight years.
However, it suffered a reduction in sales of Plavix last year, which were down from €641m in 2010 to €414m in 2011.
“Under the proposal the plant, which makes solid dose oral medications mainly for UK and European markets, would be scheduled to close by mid-2015,” said the statement.
“The products manufactured at the Fawdon site have been adversely impacted by other factors, including generic competition, resulting in a fall in demand and production volumes.”
Staff, upon hearing the announcement, left the plant in tears. Unite’s Bob Bolam said the decision had come as a surprise to employees and the union. “We are looking to work with the company to mitigate any losses and to help the surrounding area which is obviously going to be devastated by the loss of the jobs,” he said.
Sanofi currently employs around 1,800 people in the UK, including 300 staff at its UK headquarters in Guildford.