title: Crystallinity and dissolution rate of tolbutamide solid dispersions prepared by the melt method.
abstract: The influence of cooling rate of solid dispersions prepared by the melt method was studied by X-ray diffraction and scanning electron microscopy. Tolbutamide was the model drug investigated, and the carriers included urea and polyethylene glycol 6000. Slow-cooled urea dispersions of tolbutamide demonstrated a complete lack of crystallinity, suggesting the formation of an amorphous material. The rapidly cooled dispersion showed peaks for urea and an absence of drug in the X-ray pattern, suggesting that a true molecular dispersion was formed. The X-ray patterns of rapid- and slow-cooled dispersions of tolbutamide and polyethylene glycol 6000 demonstrated that a physical mixture of drug and carrier resulted from both methods of dispersion preparation.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D012459:Salicylates / Q000032:analysis; D020156:Salicylic Acid; D012995:Solubility; D000077589:Sulfathiazole; D013432:Sulfathiazoles / Q000032:analysis; D014044:Tolbutamide / Q000032:analysis*; D014961:X-Ray Diffraction
chemical_list: D012459:Salicylates; D013432:Sulfathiazoles; D014044:Tolbutamide; D020156:Salicylic Acid; D000077589:Sulfathiazole