Liquid Crystalline Phase & its Pharma Applications
Liquid crystals are the materials that are in many ways intermediate between the liquid and solid states. Liquid crystals exhibit different molecular arrangements than the liquid and solid states. The liquid crystalline state may result either from the heating of solids (thermotropic liquid crystals) or from the action of certain solvents or solids (lyotropic liquid crystals).The two main types of liquid crystals are: smectic (soap like or grease like) or nematic (threadlike). LC based systems can provide specific advantages of thermodynamic stability, high solubilisation levels, improved bioavailability, protection against oxidation and controlled release properties to the pharmaceuticals. Thus material characterization and understanding of the liquid crystalline states of active pharmaceuticals can yield wide range of options to enhance formulation performance for drug delivery. Liquid crystal materials are unique in their properties and uses. As research into this field continues and as new applications are developed, liquid crystals will play a vital role in modern technology. The purpose of this review is to focus on types, properties and applications of liquid crystals. LCs based delivery systems such as creams, ointments, gels, liposomes, colloidal dispersions and transdermal patches have been used in pharmaceuticals and cosmetics. Liquid crystals have many applications in fields of science, engineering and device technology.