Wal-Mart announced Thursday that it will sell select generic prescription drugs at a sharply reduced price in all of Florida starting Friday, nearly four months earlier than expected.

The world's biggest retailer is already selling 291 generic medications at a price of $4 for a month's supply at its stores in the Tampa Bay area. Critics say that number is misleading and only amounts to about 125 different drugs because Wal-Mart counted the same drug in different dosages to come up with its total.

A trade association of independent pharmacies that compete with Wal-Mart (WMT) said the program offers just a fraction of the roughly 8,700 generic drugs approved by the U.S. Food and Drug Administration.

"It's a loss-leader type program that is solely aimed at getting people in the door at Wal-Mart. Most people going to get their prescriptions filled will be disappointed," said Charlie Sewell, executive vice president of government affairs at the National Community Pharmacists Association. The NCPA says it represents about 24,000 non-chain pharmacies.

Wal-Mart announced the Tampa Bay program two weeks ago, and Wal-Mart executives said at the time they would look to expand the program statewide in January, and nationwide after that.

But Wal-Mart Stores Inc. executives said Thursday customer demand and requests from Florida officials led them to expand the program throughout the state.

The list of drugs has also been expanded to 314 medications, Wal-Mart said Thursday. It said that covered 143 "compounds," which the NCPA said meant 143 individual drugs in various dosages.

Consumers could save an average of 20 percent, and up to 90 percent on some prescriptions under the Wal-Mart program. The drugs covered are used to treat conditions ranging from high-blood pressure to allergies.

It is the latest health initiative by Wal-Mart since late last year as the nation's largest private employer seeks to deflect union-backed criticism of its worker benefits and influence the national debate on health care.

"If there's one thing we've learned in the past two weeks, it's that Wal-Mart can play a unique role in responding to the needs of our customers who have struggled for too long with the high costs of prescription medications," said Bill Simon, executive vice president of Wal-Mart's professional services division. "This introduces competition to an area where there has not been enough of it."

Simon said the source of the company's prescription drugs would not change. Some are domestically produced, and some are imported from abroad. He did not name specifically where the drugs come from.

"We don't do anything different than anyone else does," Simon said.

He said that within 10 days of the Sept. 21 launch of the program in the Tampa Bay area, Wal-Mart filled 36,000 new prescriptions. He said the company hopes to expand the program beyond Florida "to as many states as possible" in the weeks ahead.

Gov. Jeb Bush challenged the company to roll out the program across the state, and Wal-Mart responded, Simon said. Bush praised Wal-Mart for the program at a news conference Thursday.

"This is a disruptive idea that is going to bring benefits to millions across our state. When you're big it's easy to be a target I guess," Bush said.

Wal-Mart shares fell $1.24, or 2.5 percent, to $48.31 in afternoon trading on the New York Stock Exchange.