Solid-state properties and crystal structure of gliclazide.

The solid-state characterization of gliclazide, for which no analytical standard was previously available, has been completed by extensive structural and physical analytical examination. The crystal and molecular structure for gliclazide was determined by single-crystal X-ray diffraction. Gliclazide crystallizes in the monoclinic space group P2(1)/n, with the unit cell dimensions a = 10.828(2) A, b = 14.342(19) A, c = 11.005(6) A, and with beta = 106.97(2) degrees, V = 1635(12) A3, and Z = 4. The gliclazide molecule is articulated in an open extended conformation about the sulphonylurea nucleus. Two gliclazide molecules form a complex with one calcium atom to facilitate the transport of calcium ions across the pancreatic beta cells necessary for the stimulation of insulin secretion. The only conformation that allows for the close apposition of the tolyl groups, and therefore the formation of the gliclazide:calcium complex, is the extended conformer.