Shares in Danish pharmaceutical group H. Lundbeck plummeted Monday after it said it would be up to two years late in submitting a new anti-depressant to US authorities for approval.
The company, which is developing the drug in conjunction with the Japanese firm Takeda, said the delay was due to unconvincing initial results from three clinical studies for the new Lu AA21004 drug.
The medication is being developed to replace the most widely used antidepressant, Celexa/ Lexapro.
Lundbeck shares were down more than 13.5 percent on the Copenhagen exchange at mid-morning.
Company chief Ulf Wiinberg said Lundebck did not yet have plans for further tests and would discuss the matter with Takeda.
The company said in a statement that "Lundbeck and Takeda will continue to work with the US Food and Drug Administration and other regulatory agencies on the clinical development program and submission plans."
Depression affects 121 million people around the world, according to Lundbeck.