As Facebook gradually opened pharmaceutical industry pages to public commenting this week, some companies said they had not yet seen troublesome comments, while others continued to move offline to avoid potential risks. Facebook reversed a policy that exempted all drug company pages from open Walls. Pages focused on companies themselves and on disease or patient-specific communities are now open to comments, while those focused on a specific prescription product continue to be closed. Companies have worried that open Walls may lead to the reporting of bad side effects, promotion of off-label use or inappropriate statements — all of which could raise concern from government regulators.