The FDA, in a to drug-maker Novartis Pharmaceuticals July 29, tells the company that its use of Facebook Share to promote Tasigna is incomplete and misleading.

This is likely the first time the FDA has issued a warning to a pharmaceutical firm for using Facebook to promote its products, said Jeffrey Chester , a privacy advocate and executive director of the Center for Digital Democracy.

The FDA, which posted the warning letter on its website this week, asks Novartis to stop using Facebook Share to promote the leukemia drug.

"The shared content is misleading because it makes representations about the efficacy of Tasigna but fails to communicate any risk information associated with the use of this drug," said the FDA letter, signed by Karen Rulli, acting group letter of the agency's Division of Drug Marketing, Advertising, and Communications. "In addition, the shared content inadequately communicates Tasigna's FDA-approved indication and implies superiority over other products."

FDA rules require that most medication promotional pieces contain information about risks associated with taking the drug, the letter said. In addition, promotional materials are misleading if they suggest a "drug is safer or more effective than another drug when this superiority has not been demonstrated by substantial evidence or substantial clinical experience," the letter said.