Denmark’s H Lundbeck said today it will put back filing for approval of its new schizophrenia drug bifeprunox until 2008 in Europe as it carries out additional Phase III testing.

Bifeprunox was originally scheduled to be filed for US, Canadian and European approval in 2006, and launched in these markets in 2007. In a statement, Lundbeck said: “further clinical work will be needed to clarify the clinical profile and strengthen the registration dossier.”

Lundbeck said the timing of an application will now depend on ‘the completion of additional Phase III comparative clinical work.'

Bifeprunox was originally developed by Belgian company Solvay, which licensed European rights to Lundbeck and US rights to Wyeth last year. Solvay said earlier this year that it believes bifeprunox has blockbuster potential in the treatment of schizophrenia, and could also be used to treat other diseases, such as bipolar disorder.

The Belgian firm put out its own statement acknowledging the delay in Europe and noting that Wyeth is ‘continuing to assess and analyse the clinical study data with respect to a US filing in 2006’.

Shares in Lundbeck and Solvay were both affected in mid-morning trading today, down 8% and 7%, respectively.

Bifeprunox is a novel compound, acting as a dopamine D2 and serotonin 5-HT1A partial agonist, and is expected to have an improved safety profile over existing antipsychotic medications, including no weight gain, and no QTc prolongation, which can increase the risk of developing abnormal heart rhythms.

Results in clinical trials to date in patients with schizophrenia, suggest that it has significant antipsychotic activity compared to placebo and is generally well tolerated, said Lundbeck.

Last week, ING upgraded its rating for Lundbeck from hold to buy on the back of bifeprunox’ potential, suggesting the drug had the potential to become a first-line treatment for schizophrenia with sales of $2 billion by 2012, with Lundbeck’s share around $500 million.