A Bulgarian border policeman stands near a barbed wire wall on the border with Turkey in July 2014. Experts believe that about two-thirds of the heroin that enters Europe comes through Bulgaria, and that a third of that moves on to the United States. Dimitar Dilkoff/AFP/Getty Images hide caption

itoggle caption Dimitar Dilkoff/AFP/Getty Images

Hydrocodone, sold as Vicodin and other brand names, may face tighter restrictions on prescribing and use. Toby Talbot/AP hide caption

itoggle caption Toby Talbot/AP