Shire is now gearing up to re-file its attention-deficit hyperactivity drug SHP 465 in the US by the end of this year, on the back of new data further backing its safety and efficacy.

The drug, which was first filed in the US back in 2006, has the same active ingredient as the firm's Adderall XR (mixed amphetamine salts), but is designed to provide symptom control for adults with ADHD for up to 16 hours as opposed to its predecessor's 12.

Topline results from the 306 study, which involved 275 adults with ADHD aged 18-55 years, showed that primary endpoints were met for both doses of SHP465 being tested (12.5mg and 37.5mg, administered once daily), indicating superiority over placebo symptom improvement.

Significant improvement in those treated with the drug over placebo was also observed in patients' global functioning, Shire noted.

On the safety side, treatment-emergent adverse events occurring in greater than 5 percent for either dose of SHP465 were decreased appetite, dry mouth, insomnia, headache, anxiety, irritability and bruxism. According to the firm, adverse events were generally mild to moderate in severity and similar to those observed in previous studies.

Including study 306, Shire now has a robust database of 16 clinical studies evaluating more than 1,600 subjects in the SHP465 programme, and is planning a Class 2 resubmission with the US Food and Drug Administration by the end of 2016, which means a potential approval in the second half of next year.