Clindamycin hydrochloride monohydrate and its ethanol solvate.

Clindamycin hydrochloride, an antibiotic of the lincomycin family, was crystallized as the monohydrate, namely (2S,4R)-2-(N-{(1S,2S)-2-chloro-1-[(3R,4S,5R,6R)-3,4,5-trihydroxy-6-(methylsulfanyl)perhydropyran-2-yl]propyl}aminocarbonyl)-4-propylpyrrolidinium chloride monohydrate, C(18)H(34)ClN(2)O(5)S(+).Cl(-).H(2)O, (I), and as the monohydrate ethanol solvate, C(18)H(34)ClN(2)O(5)S(+).Cl(-).H(2)O.C(2)H(6)O, (II). The conformation of the clindamycin molecule in both crystal structures is the same and is found to be similar to that in enzyme-bound clindamycin. The simultaneous presence of free chloride ions and water molecules in (I) and of additional ethanol molecules in (II) provides an interesting network of hydrogen bonds. The significance of this study lies in the interactions in these structures and the aggregations occurring via hydrogen bonds in the hydrated and solvated crystalline forms of the title compound.