Costco Brings Its Low-Price Magic to Employer-Paid Drug Plans

Large American retailers have long viewed health care as a potentially lucrative avenue to expand their businesses. Amazon.com Inc. introduced an online pharmacy last year while Walmart Inc. is expanding its in-store clinics. Costco Wholesale Corp. is taking a different road to health-care riches: helping make prescription drug prices less opaque for employers that spend billions of dollars a year on them.

The company best known for its cavernous warehouse stores, where it sells everything from TVs to pallets of paper towels, has become partners with Navitus Health Solutions LLC, a small pharmacy benefit manager based in ...