Gabapentin and gabapentin monohydrate

Gabapentin 1‐(amino­methyl)­cyclo­hexane­acetic acid, C₉H₁₇NO₂] is a zwitterion in the solid state. Its crystal structure involves extensive hydrogen bonding between the NH₃⁺ and COO^? groups of neighboring mol­ecules. The structure of gabapentin monohydrate 1‐(amino­methyl)­cyclo­hexane­acetic acid monohydrate, C₉H₁₇NO₂·H₂O] also involves such hydrogen bonding and, in addition, has a hydrogen‐bonding network comprising the water mol­ecules and both the NH₃⁺ and COO^? groups.