U.K.-based drug giant AstraZeneca (NYSE: AZN) is planning to lay off 135 employees at its facility in Westborough, MA, starting at the end of May and continuing through the end of 2011. The news was reported today by the Boston Business Journal, which cites a notice to state labor officials. The Westborough plant, which makes supply and packaging for allergy and asthma drugs, among other products, went through a previous round of layoffs in 2009, according to the report. Before that, AstraZeneca employed some 1,000 workers in the state between the Westborough plant and an R&D center in Waltham, MA. The new layoffs are part of a broader corporate restructuring (including 3,500 job cuts worldwide) that was announced in early 2010.