Pharmaceutical liquid crystals: the relevance of partially ordered systems.
Pharmaceutical solids have generally been characterized as either three-dimensional crystals or amorphous solids based on X-ray powder diffraction and modulated temperature differential scanning calorimetry. In contrast, fewer examples of thermotropic and lyotropic liquid crystals, or mesophases, appear in the pharmaceutical literature, and that literature teaches that the aforementioned analytical techniques should be complemented with polarized light microscopy and small-angle X-ray scattering in order to effectively identify potential liquid crystalline states. Lyotropic liquid crystals are induced by the presence of solvent, and have been extensively described elsewhere in the context of emulsion technology; however, other pharmaceutical examples are emerging. Thermotropic liquid crystals are induced by a change in temperature and are essentially free of solvent, where more pharmaceutical applications appear in the literature. In the present review the general structural characteristics that favor the formation of liquid crystalline mesophases are categorized by therapeutic target and molecular size, and the analytical means of their identification are presented.
Stevenson
Cynthia L
CL
Nektar Therapeutics, 150 Industrial Road, San Carlos, CA 94070-6039, USA.
Bennett
David B
DB
Lechuga-Ballesteros
David
D
D000682:Amyloid / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry; D000935:Antifungal Agents / Q000737:chemistry; D000970:Antineoplastic Agents / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003460:Crystallization; D016572:Cyclosporine / Q000737:chemistry; D005279:Fenoprofen / Q000737:chemistry; D007004:Hypoglycemic Agents / Q000737:chemistry; D007166:Immunosuppressive Agents; D058228:Islet Amyloid Polypeptide; D017964:Itraconazole / Q000737:chemistry; D050866:Liquid Crystals / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry*; D008727:Methotrexate / Q000737:chemistry; D009254:Nafcillin / Q000737:chemistry; D019999:Pharmaceutical Solutions / Q000737:chemistry*; D044367:Phase Transition; D012997:Solvents; D044366:Transition Temperature
D000682:Amyloid; D000900:Anti-Bacterial Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000935:Antifungal Agents; D000970:Antineoplastic Agents; D007004:Hypoglycemic Agents; D007166:Immunosuppressive Agents; D058228:Islet Amyloid Polypeptide; D046911:Macromolecular Substances; D019999:Pharmaceutical Solutions; D012997:Solvents; D017964:Itraconazole; D009254:Nafcillin; D016572:Cyclosporine; D005279:Fenoprofen; D008727:Methotrexate