On Monday, Woodland Hills-based Health Net announced plans to sell its Medicare Part D prescription drug plan business to CVS Caremark for $160 million. Health Net said it expects to net $140 million cash from the sale of its PDP business, which has about 400,000 customers in 49 states and the District of Columbia, and generates about $490 million in annual revenue. The acquisition, which requires CMS approval, is expected to close in the second quarter of this year.