The FDA released a draft document on how companies can respond to off-label remarks in social media . Basically, medical staff from the company can acknowledge the off-label post only if the post is unsolicited and mentions the product name.
When communicating with the user, the public response can only include contact information with full disclosure about the medical staff's relationship with the company. The rest of the communication has to be directly with the user, through private channels; and it should include standard response information.
Understandably, sales and marketing cannot be involved in these communications.But I hope that future guidance from FDA gives companies ways to share information publicly that can guide all social media readers towards verified information.