Supernus Pharmaceuticals' SPN-812 has generated promising efficacy and safety data and several features may differentiate it from market leader Straterra, Jefferies analyst David Steinberg tells investors in a research note. The analyst estimates sales could reach $500M or more over time post a projected 2020 launch. The overall adult attention-deficit/hyperactivity disorder market remains "very large" and within the category, non-stimulant drugs represent a "major opportunity" and the two FDA approved drugs available are "suboptimal," Steinberg contends. He keeps a Buy rating on Supernus with a $58 price target.