Most pharmaceutical companies don’t let the general public post on their pages’ Facebook walls, and in fact didn’t join the social network until they were given permission to block those posts. Facebook is changing policies now, though, and forcing the companies to have open walls for Facebook users to post comments. The Washington Post reports that AstraZeneca and Johnson & Johnson have already shut down pages that they fear will not benefit from the open wall policy, as posts from users describing adverse side effects or negative experiences might hurt business or create legal difficulties.