The Food and Drug Administration has decided to allow Florida to import millions of dollars worth of medications from Canada at far lower prices than in the United States, overriding fierce decades-long objections from the pharmaceutical industry, according to a senior administration official.

The approval is a major policy shift for the United States, and supporters hope it will be a significant step forward in the long and largely unsuccessful effort to reign in drug prices. Individuals in the United States are allowed to buy directly from Canadian pharmacies, but states have long wanted to be able to purchase medicines in bulk for their Medicaid programs, government clinics and prisons from Canadian wholesalers.

Florida has estimated that it could save up to $150 million in its first year of the program, importing medicines that treat H.I.V., AIDS, diabetes, hepatitis C and psychiatric conditions. Other states have applied to the F.D.A. to set up similar programs.

But significant hurdles remain. The pharmaceutical industry’s major lobbying organization, the Pharmaceutical Research and Manufacturers of America, or PhRMA, which has sued over previous importation efforts, is expected to file suit to prevent the Florida plan from going into effect. Some drug manufacturers have agreements with Canadian wholesalers not to export their medicines, and the Canadian government has already taken steps to block the export of prescription drugs that are in short supply.

“Canada’s drug supply is too small to meet the demands of both American and Canadian consumers,” Maryse Durette, a spokeswoman for Health Canada, wrote in an email message. “Bulk importation will not provide an effective solution to the problem of high drug prices in the U.S.”

Congress passed a law allowing drug importation two decades ago, but federal health officials delayed implementing it for years, citing safety concerns, one of the main arguments drug companies have used against it. In 2020, President Donald J. Trump pushed the law forward, announcing that states could submit importation proposals to the F.D.A. for review and authorization. President Biden added momentum the following year, instructing federal officials to keep working with states on importation plans.