Forest Laboratories’ investigational drug for treating neuropathic pain associated with diabetic peripheral neuropathy has failed to meet the primary endpoint of its Phase II trial.

Radiprodil (RGH-896) did not demonstrate clinically meaningful reductions in mean daily pain scores compared to a placebo for any dosage studied.

The trial involved 458 adults with diabetic peripheral neuropathy, who were randomised to one of three radiprodil doses (15mg, 30mg or 45mg), an active comparator or a placebo, three times a day for 14 weeks.

The most common adverse events after treatment with radiprodil were dizziness, fatigue and insomnia.

Radiprodil is an orally active NR2B (a sub-unit of the NMDA receptor) antagonist discovered by Gedeon Richter, who are co-developing the drug with Forest Laboratories.

The two companies will review the study again to plan the next steps in development.