* Requests change in efficacy analysis
* Says study may not reach enrollment goals before yr end
* Another study shows drug reduces viral concentration
* Shares down 9 pct (Recasts, updates share movement)
Jan 13 BioCryst Pharmaceuticals Inc (BCRX.O) delayed enrollment in a late-stage study of its key experimental influenza drug and sought more funds from the U.S. health department, sending its shares down 7 percent.
BioCryst also requested a change in the way it analyzes the drug's efficacy and said it was unlikely the study will reach its enrollment goal before 2011 end.
The drug, peramivir, is being developed under a $180 million contract from the Biomedical Advanced Research and Development Authority within the U.S. Department of Health and Human Services.
The study aims to evaluate the efficacy of peramivir when administered intravenously once daily along with the standard of care, versus the standard of care alone.
The company also said another late-stage study showed that peramivir reduced virus concentration. Preliminary data from the study also showed the drug was safe and well-tolerated.
U.S. health regulators have already authorized peramivir for emergency use in the treatment of H1N1 infection.
BioCryst shares were down 9 percent at $4.71 in morning trade on Thursday on Nasdaq. (Reporting by Shravya Jain in Bangalore; Editing by Vinu Pilakkott)