An alternate crystal form of gabapentin: A cocrystal with oxalic acid

A cocrystal of gabapentin and oxalic acid has been prepared employing a strategy based on a hydrogen-bonded synthon described by the graph set notation R-4(2) (8). High throughput techniques and solvent drop grinding were used along with traditional crystallization methods, including crystallization in aqueous Solutions at various pH. A number of new solid forms have been detected. The cocrystal of gabapentin and oxalic acid was fully characterized including single crystal structure analysis, which revealed the R-4(2)(8) synthon.