Medicine can be life saving, or poisonous. Can we come by the medicines we take without human guinea pigs? Where we once used prisoners, now there is a subculture of volunteers. Michael Palmieri and Donal Mosher, directors of the much lauded October Country are back with a haunting document of the “off label” world. Off Label premiered this weekend at the Tribeca Film Festival and is on to competition in Hotdocs in Toronto and then the San Francisco International Film Fest. Justin Stewart reviews.