Pseudopolymorphism of levodopa: A novel “disappearing” dihydrate

• A novel dihydrate of levodopa is reported.
• The structural characterization of the novel dihydrate shows water molecules lying within a cage-like structure.
• The novel dihydrate transforms into the anhydrous form.

We report herein the crystal structure of a novel l-dopa dihydrate, an unstable pseudopolymorph detected in some co-crystallization studies. This form is obtained by traditional solution techniques and tends to convert to the anhydrous form under ambient conditions. Even though pseudopolymorphism has generally been subject of large conceptual discussions, it is indeed of importance in the pharmaceutical industry and, in this particularly case, the knowledge of the formation of this novel dihydrate may be very relevant for processing issues.

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