GlaxoSmithKline will begin laying off its workforce at a drug-manufacturing plant in Bristol in April 2009 and shutter the plant by Oct. 31, the company said Wednesday.

The 400,000-square-foot plant makes the penicillin drug Augmentin.

GSK first announced plans in 2006 to close the plant due to declining sales of Augmentin. The plant currently employs 236 people. At its peak, the plant had more than 400 workers, according to the Herald-Courier newspaper in Bristol.