Aetna Inc. and CVS Caremark Corp. are jointly offering a U.S. Medicare prescription drug plan, the latest such arrangement between a health insurer and a drugstore chain.

Coventry Health Care Inc. said over the weekend it would offer a Medicare drug plan in 2012 with Walgreen Co. and discount retailers Wal-Mart Stores Inc and Target Corp., which have pharmacies in their stores.

The Aetna plan, which the companies announced Monday, has no deductible for generic drugs and will cost $26 per month in premiums. The Coventry plan has an average monthly premium of $25.60 and no annual deductible.

A year ago, Humana Inc and Wal-Mart teamed up for a Medicare drug plan.

The Aetna-CVS plan deepens the companies' relationship. Last year, CVS landed a 12-year deal to manage some pharmacy benefits for about 9.7 million Aetna pharmacy members and administer about $9.5 billion in annual drug spending.

Medicare, the U.S. government health coverage program for the elderly and disabled, began offering a drug benefit, known as Medicare Part D, in 2006 through private plans approved by the government.