Two large pharmaceutical manufacturers plan to reinstate discounts for low-income Medicare enrollees after receiving assurance from the federal government that they won't have to give the same discounts to Medicaid patients.

Bristol-Myers Squibb Co. and GlaxoSmithKline PLC also said yesterday that they will mail refund checks to members of the discount program, known as Together Rx, who paid higher prices for these companies' previously discounted drugs in recent weeks.

On Oct. 1, the companies raised prices for some drugs, saying they couldn't afford to comply with a federal law that seemingly required them to offer the same savings to Medicaid enrollees. Medicaid is a government insurance program for the poor; Medicare is primarily for the elderly.

At the time, Thomas A. Scully, who monitors compliance with that law as head of the government's Centers for Medicare & Medicaid Services, said the drugmakers were mistaken in raising their prices. Five other companies that participate in Together Rx did not raise prices.

Yesterday, executives of Bristol-Myers and GlaxoSmithKline said they received written assurance from Scully that the law did not apply to Together Rx. Bristol-Myers executives said the discounts were reinstated yesterday. Glaxo said the savings will be reinstated within 10 days.

"I wish we didn't have that confusion," Scully said yesterday. "But that stuff happens."

The Together Rx card is offered to Medicare patients who do not have drug coverage and whose incomes do not exceed $28,000 for a single person or $38,000 for a couple. More than 333,000 people have signed up, a spokesman for the program said.