The main Irish unit of Swiss-owned pharma giant Roche plunged into the red last year as it abandoned plans to produce a potential new blockbuster drug at its Co Clare plant.

The Clarecastle firm booked a €18.6 million impairment after the company's parent, Roche, decided to end all activities concerning the production of a new drug, Dalcetrapib, in May 2012.

According to returns just filed with the Companies Office, Roche Ireland Ltd recorded a pretax loss of €10.5 million for the year. This followed a pretax profit of €222,717 in 2011.

The new drug was slated for production at Clarecastle and preparatory work was well advanced. Planning permission had already been secured by Roche for the facility’s expansion to cater for the production of the “good cholesterol” drug designed to combat heart disease. However, Roche decided to abandon the trials.

Before the impairment charge and non-cash depreciation costs of €12.56 million, the Irish business recorded earnings of €21.9 million.