Alcobra's experimental therapy for the treatment of attention-deficit hyperactivity disorder in adults has failed to hit targets in a late-stage trial, throwing a shadow of doubt over the future of the company.

The Israeli drugmaker said top-line results from the Phase III MEASURE trial failed to show a statically significant difference between Metadoxine Extended Release (MDX) and placebo in the change from baseline of the investigator rating of the Conners' Adult ADHD Rating Scales (CAARS), and that it would this end its development.

"We are exceedingly disappointed with these top-line results," noted Dr Yaron Daniely, president and chief executive of the firm. He said the company will carry out a full review of data in the coming weeks before unveiling a new strategic plan for investors.

The news comes just days after the firm announced on January 9 that US regulators agreed to modify the Clinical Hold on the drug from Full to Partial to allow the conduct of a Phase I safety study to assess the potential relevance of adverse findings observed in long-term, animal studies of metadoxine with regard to human exposure.

"We are encouraged by this productive meeting with the FDA and the progress made in outlining the development path for a future NDA submission of MDX for treatment of paediatric and adult ADHD," Dr Daniely said at the time.

Shares in the firm dropped more than 50 percent on the news that the drug had failed to meet efficacy targets.