title: Thermosensitive Drug Permeation through Liquid Crystal-Embedded Cellulose Nitrate Membranes.
abstract: In this study, the application of thermotropic liquid crystals embedded in cellulose nitrate membranes as on-off drug permeation control in response to temperature changes is described. Two low-molecular-weight liquid crystals, n-pentyl-cyanobiphenyl (K15) and n-heptyl-cyanobiphenyl (K21), with nematic-to-isotropic phase transition temperatures (T(n-i)) of 36.3 °C and 43.3 °C, respectively, were used to modulate drug permeation through the membrane. Liquid crystal-embedded membranes composed of appropriate blends of K15 and K21 were prepared by vacuum filtration. The permeation of pyrazinamide and metronidazole as drug models with different hydrophilicity and molecular weights through the liquid crystal-embedded membrane was examined. It was found that the drug permeation through the membrane could be modulated by changing the temperature below and above the T(n-i) of liquid crystals. The permeation of pyrazinamide, the hydrophilic drug with smaller molecular weight, was more temperature-dependent than metronidazole, the hydrophobic drug with higher molecular weight. These experiments were also repeated with thermal cycling between 25 °C and 45 °C. The permeation profiles were reversible and followed zero-order kinetics.
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Afrouz
authors.initials: A
authors.lastname: Yousefi
authors.forename: Elham
authors.initials: E
authors.lastname: Khodaverdi
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Atyabi
authors.forename: Rassoul
authors.initials: R
authors.lastname: Dinarvand
mesh_terms: D002482:Cellulose; D003101:Collodion; D007700:Kinetics; D050866:Liquid Crystals / Q000737:chemistry; D008566:Membranes; D008970:Molecular Weight; D044367:Phase Transition; D013696:Temperature; D044366:Transition Temperature
chemical_list: D002482:Cellulose; D003101:Collodion