Vicksburg’s Wal-Mart SuperCenter joined hundreds of other Wal-Marts nationwide Thursday in what is perhaps the largest-ever cut in prescription drug prices.

Under the plan, already in effect in 15 states, the store’s pharmacy has a flat price of $4 to fill any prescription with the generic form of 143 different medicines in 314 dosages, including liquid or solid forms.

Bobby Shumpert, manager of Vicksburg’s Wal-Mart, said the pharmacy here started filling prescriptions at the $4 price as customers began to learn of the company’s announcement.

Mississippi was one of 12 states added to the program by the discount retailer based in Bentonville, Ark.

The amount customers stand to save at the $4 price varies from a few dollars per month to possible hundreds, depending on the condition being treated and retail prices.

Thursday, the Vicksburg store was among 1,008 stores added to the program, rolled out in Florida three weeks ago. The low-priced drugs are now available in 2,507 Wal-Mart, Sam’s Club and Neighborhood Market stores.

The company said in a news release that it accelerated the launch of the low-priced prescriptions because of customer demand.

Analysts say the program will help Wal-Mart by bringing in more customers who will shop in other store departments, and extend its reach in another segment of the retailing industry – the drug store business.

Union-backed Wal-Mart critics have also accused the company of using the low-priced drugs to divert attention from its own employee health insurance plan, which anti-Wal-Mart groups say does not offer adequate coverage.

The $4 price does not apply to brand-name drugs for which no generic form is available or when a physician chooses not to allow a generic alternative to a prescribed medicine.

In addition to Mississippi, states added Thursday were Alabama, Georgia, Iowa, Kansas, Maryland, Michigan, Missouri, New Hampshire, Ohio, South Dakota and Virginia.

States already with the program were Alaska, Arkansas, Arizona, Delaware, Florida, Illinois, Indiana, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Texas and Vermont.

The Associated Press contributed to this report.