This year's FDA approval of Horizant (gabapentin enacarbil) for restless legs syndrome came with a twist: XenoPort Inc. and partner GlaxoSmithKline plc originally developed and submitted the drug for approval via the "traditional" 505(B)(1) pathway; only after receiving a complete response letter did the firms shift their strategy, refile via the 505(B)(2) pathway, and gain approval. (See BioWorld Today, Feb. 19, 2010, and April 8, 2011.)