* Sees $4.2 mln charge in 2010 H1
* Expects to save about $15.6 mln annually
* Shares down 4 pct
March 5 (Reuters) - XenoPort Inc XNPT.O said it would cut its workforce by about 50 percent to focus on the development of its product candidates, and would take a related charge of $4.2 million in the first half of 2010.
As of Dec. 31, 2009, XenoPort had 219 full-time employees, according to a regulatory filing.
The company said it would save about $15.6 million yearly from the restructuring.
XenoPort will focus on the approval process of its restless leg syndrome drug, Horizant, complete its ongoing mid-stage trial of arbaclofen placarbil in gastroesophageal reflux disease and start a mid-stage trial of XP21279 for Parkinson's patients.
Last month, the U.S. Food and Drug Administration issued a complete response letter for Horizant -- a long-lasting version of the drug gabapentin that is approved for refractory epilepsy -- citing a potential link to cancer found in rats.
Shares of the company fell 4 percent to $7.56 Friday afternoon on Nasdaq. (Reporting by Anand Basu in Bangalore; Editing by Ratul Ray Chaudhuri)