Targacept TC-5619 has not met the primary outcome measure in a Phase II trial in patients with inattentive-predominant attention deficit/hyperactivity disorder (ADHDi).

The primary outcome measure of the placebo-controlled trial was change from baseline on the inattention subscale of the Conners’ Adult ADHD Rating Scale-Investigator-Rated (CAARS-INV), after four weeks of treatment versus placebo.

TC-5619 exhibited a similar safety and tolerability profile as of placebo but the placebo dose group patients showed consistent improvement compared to TC-5619 dose group patients.

Targacept board chairman Mark Skaletsky said TC-5619 did not meet the goal in the ADHDi study.

"Based on these results, we have made the determination that we will not pursue further development of TC-5619 in ADHD," Skaletsky said.

"Under these circumstances, we are taking additional steps to more closely align our resources with our current operational plan and emphasize the efficient use of Targacept’s capital.

"We will limit our investment in our nicotinic pipeline to our ongoing or previously announced clinical programs until the search for a new CEO is successfully completed, and we will implement a further reduction in force."

The double blind, parallel group study randomised 175 patients with ADHDi, ages 18 to 65, of which 153 completed the study.

The study design provided for a four-week screening period, after which patients were randomised into one of three cohorts and received either placebo or one of two doses of TC-5619 (5mg or 25mg) once daily for four weeks in a ratio of 2:1:1 (placebo: low dose: high dose).