Walgreen Company customers have filed a lawsuit in California this week accusing the national drug-store chain of unlawfully selling medical information gleaned from patient prescriptions, Reuters Legal reports.

This lawsuit takes the controversial issue of data-mining de-identifed patient data to a new level. The plaintiffs aren't concerned about privacy. They're going after the comercial value of their prescription information, which they claim Walgreens has taken from them, according to Reuters.

The story originally broke March 15 on the Westlaw News and Insite website.

According to Reuters Legal, the Walgreen Company (known as Walgreens) sells the prescription information to data mining companies who resell it to pharmaceutical companies for marketing purposes. This allows drugmakers to target physicians considered high-volume prescribers and those most willing to prescribe new medications.

Walgreens spokesman Robert Elfinger said the company had just learned of the lawsuit and declined to comment, Reuters reported.

[Read how data mining companies say it is their their right to sell patient data.]

The suit cites Walgreen's 2010 annual filing with the Securities and Exchange Commission, which lists "purchased prescription files" as intangible assets worth $749 million.

Data-mining of de-identifed patient data is a common practice in the U.S. Terry Baynes, author of the Reuters article, said similar class action lawsuits have surfaced elsewhere in the country regarding the commercial value of de-identified patient data.

[See also: Walgreens employs mobile tech to drive better care.]