But federal regulators contend the latest strategy — which relies on a creative interpretation of drug safety laws — is illegal.

The Federal Trade Commission recently weighed in on a legal case over the tactic involving the drug maker Actelion, and earlier this month a federal suit was filed in another case in Florida.

“We definitely see this as a significant threat to competition,” said Markus Meier, who oversees the commission’s health care competition team.

The new approach is almost elegant in its simplicity: brand-name drug makers are refusing to sell their products to generic companies, which need to analyze them so they can create the copycat versions. Traditionally, the generic drug makers purchased samples from wholesalers. But because of safety concerns, an increasing number of drugs are sold with restrictions on who can buy them, forcing the generic manufacturers to ask the brand-name companies for samples. When they do, the brand-name firms say no.

Brand-name companies say they are protecting themselves — and patients — in case the drugs are somehow used improperly. They say no law requires one company to do business with another.

Advocates for generic drugs say the practice could limit access to the low-cost drugs, which they say have saved more than a trillion dollars over the last decade. They say the companies that have most aggressively pursued the tactic tend to be those with drugs that are nearing the end of their patent life.

Actelion, a Swiss company, is withholding samples of its flagship product, Tracleer, which treats a lung disorder. Its patent is set to expire in 2015. The company’s other product in question, Zavesca, has a patent that expires later this year. Tracleer costs about $79,000 a year, while Zavesca costs about $229,000.

The issue has its roots in a 2007 law that allowed the Food and Drug Administration to require detailed safety programs for drugs with serious side effects or the potential for abuse. In many cases, those programs simply direct the company to educate doctors or patients about risks. But in other cases, they require that distribution be limited to approved pharmacists and health care providers.

About 70 drugs carry mandatory drug safety plans, and of those, 34 have more restrictive requirements, according to the F.D.A.

Although the 2007 law said the programs should not be used to block development of generic drugs, brand-name companies said the language was vague and began restricting access to drug samples soon after it was passed.

In 2009, generic companies began complaining that Celgene had refused to sell them samples of Thalomid, the drug better known as thalidomide that is now used to treat cancer and leprosy, and a related drug, Revlimid. Lannett, a generic company, sued Celgene, claiming its practices were anticompetitive, and the case was settled. The trade commission and the Connecticut attorney general started investigations, which Celgene has said are still under way.

At least one company, Gilead Sciences, explicitly restricts access to samples. Pharmacies and other institutions that buy its drug Letairis, which treats a serious lung condition, must agree not to “use product in clinical trials or other studies without the prior written consent of Gilead Sciences,” according to an order form sent to customers by Accredo, a specialty pharmacy that distributes Letairis for Gilead. A spokesman for Gilead declined to comment.

Brand-name manufacturers are also limiting access to drugs even when the government does not require it. In a federal lawsuit filed April 1 in Florida, Accord Healthcare, an Indian generics manufacturer, said the drug company Acorda refused to turn over samples of its multiple sclerosis drug Ampyra, even though there are no restrictions on its distribution.

In a letter to Accord from Acorda that was submitted to the United States District Court for the Southern District of Florida, in Fort Lauderdale, Acorda echoed other companies’ positions and said it was under no obligation to sell its products to another manufacturer.

Apotex, a Canadian company, said the drug maker Novartis denied it access to Tasigna, a leukemia drug, until Apotex threatened to sue. Another company, Lundbeck, has so far declined to provide Apotex with samples of the drug Xenazine, which treats a movement disorder caused by Huntington’s disease.

Julie Masow, a spokeswoman for Novartis, said Apotex ultimately purchased samples of Tasigna through the drug’s sole distributor. She said the delay was the result of a misunderstanding, adding “generic companies are free to buy Novartis products through distribution channels.”

Representatives of brand-name manufacturers say there are good reasons to restrict drugs to approved pharmacies or health care providers. Lundbeck said it sells Xenazine, also known as tetrabenazine, to a limited network of specialty pharmacies because it treats fewer than 25,000 people nationwide.

“Not many retail pharmacies would stock the product for so small a patient population,” said Sally Benjamin Young, a spokeswoman for Lundbeck.

Article source: http://www.nytimes.com/2013/04/16/business/drug-makers-use-safety-rule-to-block-generics.html?partner=rss&emc=rss