Shares of Alkermes /zigman2/quotes/205084517/composite ALKS -1.55% were down 2.74% after the Food and Drug Administration published a warning letter alleging Vivitrol ads didn't include important risk information. If Vivitrol, which is used to prevent relapses in opioid addiction and is the drugmaker's top-selling drug, is used in conjunction with a previously tolerated dose of opioids, it can lead to an overdose. That information was not included in a print ad marketing the drug to the criminal justice system. The FDA told Alkermes to stop publishing the ad and to submit a response to the regulatory agency by Dec. 16. "The criminal justice system is an important aspect for us as people are more and more focused obviously on drug offenses and as opposed to violent offenses, how people can get treatment behind the walls. The prison system in the United States is not set up to deliver treatment," CFO James Frates told investors in July, according to a FactSet transcript of a Q2 earnings call. Vivitrol brought in $85.1 million in sales in the third quarter of 2019, up from $79.9 million in the same period in 2018. Alkermes' stock has dropped 29% year-to-date. The S&P 500 /zigman2/quotes/210599714/realtime SPX -0.0067% is up about 25%.