UPDATE 1-Acadia schizophrenia drug fails trial; stock falls

(Updates with share price, analyst and company comment)

BOSTON, June 16 (Reuters) - Acadia Pharmaceuticals Inc (ACAD.O) said on Monday its experimental schizophrenia drug did not improve symptoms of the disease in a clinical trial, sending its stock down 47 percent in early trading.

The San Diego-based biotechnology company said the drug, ACP-104, did not meet either the main goal of a mid-stage trial or any of the secondary goals, and Acadia will not conduct further trials.

It said it is continuing to develop its lead product, pimavanserin, for the treatment of Parkinson's disease psychosis as well as schizophrenia.

The company's ability to commercialize pimavanserin depends largely on its ability to link up with a deep-pocketed partner.

"This is certainly something that is important to us," Uli Hacksell, the company's chief executive, said on a conference call.

Investors, however, are getting impatient. It has been 15 months since the company reported positive data from a mid-stage trial of pimavanserin in schizophrenia.

Pimavanserin is designed to be used in combination with existing antipsychotics, allowing them to be used in smaller doses to achieve the same effect but with fewer side effects such as weight gain.

"They haven't got a partnership and there never will be a partnership," said Jonathan Aschoff, an analyst at Brean Murray Carret & Co. who believes pimavanserin does not offer sufficient benefit over Johnson & Johnson's (JNJ.N) antipsychotic Risperdal to make it a must-have for a pharmaceutical company.

Acadia shares fell $3.99 to $4.50 in early trading on Nasdaq. (Reporting by Toni Clarke; editing by John Wallace)