Recent state efforts to adopt drug formularies in workers compensation have experienced obstacles despite evidence that they can produce good results for states grappling with opioid addiction and reduce prescription costs, according to experts. Louisiana, for example, ranked second in the strength of doses among 25 states studied for injured-worker opioid prescriptions, according to Cambridge, Massachusetts-based Workers Compensation Research Institute’s 2016 figures. Yet legislative efforts to pass a drug formulary failed in early June when the state Senate did not place the issue on its calendar for consideration before the end of the legislative session.