LONDON The Food and Drug Administration has declined to approve a drug used to treat restless leg syndrome, the drug’s makers announced Wednesday.
GlaxoSmithKline and XenoPort said they had received a complete response letter for the FDA for their application for Horizant (gabapentin enacarbil) extended-release tablets submitted in January 2009. A complete response letter means that the FDA has reviewed an approval application, but questions remain that preclude its approval.
The FDA cited a finding of tumors found in the pancreas cells of rats during preclinical testing as a sufficient concern to preclude the drug’s approval. While similar problems were found when the agency approved the drug as a treatment for refractory epilepsy, it said Horizant’s benefits for refractory epilepsy patients justified the potential risks. GSK and XenoPort have said they are evaluating the letter.