Prophylactic migraine treatment GSK1838262 (gabapentin enacarbil) has failed its Phase IIb trial, demonstrating no significant improvement compared to a placebo.

In the 30-week trial, the drug did not meet its primary endpoint – a change from baseline in the number of migraine headache days during the last four weeks of treatment prior to taper.

The drug has been jointly developed by GlaxoSmithKline and XenoPort.

XenoPort CEO Ronald W Barrett said the high placebo response rate may have impacted the ability of the trial to detect the potential benefit of GSK1838262 in patients.