(Reuters) - Supernus Pharmaceuticals Inc said on Thursday its drug for attention deficit hyperactivity disorder met the main goal in a late-stage trial on adolescents, weeks after results from trials testing the drug on children failed to impress investors.

At daily doses of 200 mg and 400 mg, the drug, SPN-812, showed statistical significance in improvement in symptoms such as hyperactivity and lack of attention among 12-17 year olds, Supernus said.

SPN-812 is a non-stimulant and belongs to the same class of medicines as Eli Lilly and Co’s Strattera and Shire Plc’s Intuniv.

“SPN-812 demonstrated significant reduction in both hyperactivity and inattention sub-scales, a point of differentiation from Strattera which reportedly works better on inattention but not hyperactivity,” Mizuho analyst Irina Koffler wrote in a note, calling the data a win for the company.

The drug had also met the main goal in two other late-stage studies testing the drug in children, the company said earlier this month, but its shares had then dropped 16 percent with analysts saying the drug failed to stand out from existing treatment options for ADHD.

“We now have positive data proving the efficacy and safety of SPN-812 in all ADHD patient populations; positive Phase III data in children 6-11 years old and adolescents 12-17 years old, and positive Phase IIa data in adults,” Chief Executive Officer Jack Khattar said in a statement.

SPN-812 was well-tolerated and showed a statistically significant onset of action as early as first week into the treatment, when administered the 400 mg dose.

“In no way do we believe SPN-812 is a value detractor, and like in epilepsy, we think Supernus will execute with strong potential upside to our conservative about $220 million peak,” Stifel analyst Annabel Samimy said.

Last week, the U.S. Food and Drug Administration had expanded approved the company’s epilepsy drug Oxtellar XR to be used as a monotherapy in children aged six to 17 and in adults.

The company said it expects to announce data from the final late-stage trial of SPN-812 by the end of the first quarter of 2019, and submit a marketing application to the U.S. health regulator in the second half of 2019.

The company’s shares were up 3 percent at $34.46 in early morning trading.