Drug developer XenoPort Inc. is cutting half of its staff and eliminating drug discovery work in order to save money as it prepares to focus solely on drugs already in clinical testing, according to the Associated Press. The company will be eliminating about 110 jobs. It expects the cutbacks to save about $15.6 million per year, although it will book $4.2 million in restructuring charges in the first half of 2010 and expects other costs. In February, the Food and Drug Administration delayed approval of the company''s drug candidate Horizant, which is intended to treat restless leg syndrome. The agency cited animal study results that showed pancreatic cell tumors in rats, and said it may require XenoPort to conduct further studies of the drug before granting approval. It could also require warnings that would limit Horizant''s sales. XenoPort announced its plans Friday afternoon, and its shares fell 5.7 percent on the day. They rose 33 cents to $7.75 in Monday morning trading. The company employed 219 workers at the end of 2009. Through a partnership with GlaxoSmithKline PLC, it is developing Horizant as a treatment for moderate to severe restless legs syndrome and for nerve pain. The company said it also plans to complete a mid-stage study of a drug intended to treat heartburn, and start a mid-stage trial of a drug designed to treat Parkinson''s disease.