Temozolomide hydrochloride dihydrate

Abstract

The X-ray crystal structure of temozolomide hydrochloride shows that the dihydrate salt contains one neutral temozolomide, one temozolomide-H⁺Cl⁻, one H₃O⁺·Cl⁻, and three water molecules. This is the first crystallographic evidence of a protonated form of the antitumour drug temozolomide. The protonation of water O and imidazole N of the drug are rationalized by calculated pK_as.