Improving the Solubility of Lenalidomide via Cocrystals

An anticancer drug, lenalidomide, has low oral bioavailability (below 33%) due to its poor solubility in water. To improve its solubility, three cocrystals of lenalidomide with urea (1) and 3,5-dihydroxybenzoic acid (2, 3) were prepared. The structures of 1–3 were determined by single crystal X-ray diffraction, and they all form three-dimensional hydrogen-bonded frameworks between lenalidomide and the coformers. The apparent solubility value and intrinsic dissolution rate of lenalidomide in phosphate buffer of pH 6.8 have been improved after the formation of cocrystals. In addition, 2 and 3 can convert to each other under certain conditions.