It's been two years since the FDA passed its social media guidance for pharmaceutical advertising in limited-character formats -- that is, primarily, Twitter and Google sponsored links. Among other things, that guidance stipulated that, if a company wants to tweet about the benefit of a drug, they must include the "most serious risks" of that drug in the same tweet and that tweets must contain direct links to a more extensive list of risks and side effects.

Now the FDA is signalling that it might revisit that guidance after it gathers data on how effective it is to present risks in a link, as opposed to within the original character limit. The agency presented its plan for the study for comment in the federal registry earlier this month. It will conduct four studies, two on Twitter and two on Google ads, with a total of 6,502 participants. The studies will test consumer behavior around an ad for a fictional weight loss drug and a fictional treatment for migraines.

"The concept of linking to risk information by providing substantive product risk information on a landing page ('link to the risk information'), rather than presenting risk information together with product benefit information within the character-space-limited communication, has been the subject of legislation and has been discussed as an option by some in industry and media," the agency writes. "The studies are designed to address the question of whether substantive risk information in the character-space-limited communications is effective in communicating risks when benefit claims are made, or whether a link to the risk information is sufficient. Within each study, we will manipulate whether or not substantive risk information appears in the character-space-limited communication."

The study is high stakes for pharma. If the FDA finds that information contained within a link is retained just as well as information contained in the body of a tweet or sponsored link, that would likely drive them to amend the guidance to explicitly permit what's colloquially referred to as the "one-click rule" -- the notion that lists of risks can be one click away from a tweet or ad instead of contained within it. On the other hand, if the findings go the other way, the agency could explicitly forbid relegating safety information to a linked page. And the FDA's hypothesis is the latter.

"We hypothesize that participants who see substantive risk information in the character-space-limited communication, compared with link-only participants, will have greater retention of the risk included in the communication and higher perceived risk," the agency wrote. "We will explore whether including substantive risk information in the character-space-limited communication affects the likelihood that participants notice the communication or click the link to the risk information."

Interested parties, including pharma companies, have until January 6th to comment on the document. So far, no public comments have been posted.