Crystal structures of a new polymorphic form of gabapentin monohydrate and the e and z isomers of 4-tertiarybutylgabapentin.

Gabapentin, a widely used antiepileptic drug, crystallizes in multiple polymorphic forms. A new crystal form of gabapentin monohydrate in the space group Pbca is reported and the packing arrangement compared with that of a previously reported polymorph in the space group P2(1)/c [Ibers, J.A.