Microdialysis Techniques for Epilepsy Research
Steven L. Peterson, Timothy E. Albertson in Neuropharmacology Methods in Epilepsy Research, 2019
Many fiber-shaped dialysis materials have been successfully used in fabrication of microdialysis probes. Popular ones are regenerated cellulose, cellulose acetate, cellulose ester, polysulfone, etc.28 These membranes vary in their permeability limits, diameter, wall thickness, etc. When choosing a dialysis membrane, the primary consideration should be the permeability limit and its performance in vivo. Certain membrane materials (such as polysulfone) offer excellent in vitro recovery numbers for a given surface area, but may perform poorly in vivo, and others are vice versa. The regenerated cellulose membranes are usually rugged enough to sustain the handling required under common laboratory conditions. If the membrane must be wet in order to stay patent, threading it inside the plumbing tubes and gluing it can be tricky. Flaccidity and handling of the membrane in dry and wet conditions should be considered. The membrane should be firm enough that it can be conveniently placed inside the target tissue. Also important factors are availability of diameters that are suitable for the target tissue, and their ability to withhold internal fluid pressures. Such information is usually available from the membrane manufacturer.
Membrane Transport
Lelio G. Colombetti in Biological Transport of Radiotracers, 2020
The first membrane was a semipermeable cellulose acetate membrane. Due to the osmotic pressure difference, a large volume flow takes place to the second compartment. Hydrostatic pressure is then built up in the second compartment. The low sigma of the second (sintered glass disc) membrane does not allow back volume flow. There is therefore a net volume flow against the osmotic gradient. To sustain such an energetically unpromising situation, salt continuously has to be added to the second compartment. Otherwise, the process will stop fairly rapidly. In the artificial system this is achieved by dripping salt into the second compartment. In an epithelial system, active water transport is considered to occur by means of a “standing gradient flow system.”19 Epithelia are sheets of cells separated by long and narrow lateral intercellular spaces terminated at one end by so-called tight junctions. Solute is actively transported into these intercellular spaces, making the fluid there hypertonic. According to the Curran and Mcintosh18 analogue, the cell membrane equals the cellulose acetate membrane, the intercellular space equals the second compartment, and the interface between intercellular space and medium equals the sintered glass disc.
Topical Formulations for Onychomycosis: A Review
Andreia Ascenso, Sandra Simões, Helena Ribeiro in Carrier-Mediated Dermal Delivery, 2017
Chouhan et al. [57] studied the influence of a permeation enhancer (hydroxypropyl-b-cyclodextrin or HP-p’-CD) in a terbinafine nail lacquer formulation. This formulation was composed of cellulose acetate and ethyl cellulose as film-forming polymers, triethyl citrate as plasticizer, and isopropyl alcohol and acetone as solvents. Formulations containing this enhancer demonstrated a higher flux than the control formulation in in vitro studies. The lacquer containing 10% (w/v) HP-b-CD showed maximum flux of 4.586 ± 0.08 gg/mL/cm2 as compared to the control flux of 0.868 ± 0.06 gg/mL/cm2, demonstrating its ability to enhance the transungual permeation of poorly soluble drugs [57].
Preparation and functional evaluation of electrospun polymeric nanofibers as a new system for sustained topical ocular delivery of itraconazole
Published in Pharmaceutical Development and Technology, 2022
Saba Mehrandish, Ghobad Mohammadi, Shahla Mirzaeei
Prepared CA-PVA, PCL8, and PCL6 nanofibers are represented in Figures 1(C–E). Cellulose acetate is one of the most common biopolymers used in the development of polymeric nanofibers which can be used as drug carriers or in tissue engineering (Tan et al. 2020). This polymer can be dissolved in pure acetone but when dissolved in a mixture of acetone with another organic solvent like dimethylformamide or dimethylacetamide, fewer beads, and finer fibers may be obtained (Son et al. 2006; Taepaiboon et al. 2007). Because of the poor physicochemical properties of pure CA nanofibers like the low flexibility and tensile strength, the addition of PVA blend was considered to enhance the prepared nanofibers. After the electrospinning process, a uniform, and flexible CA-PVA nanofiber with an acceptable strength was obtained.
An analytical GC-MS method to quantify methyl dihydrojasmonate in biocompatible oil-in-water microemulsions: physicochemical characterization and in vitro release studies
Published in Pharmaceutical Development and Technology, 2018
Gisela Bevilacqua Rolfsen Ferreira da Silva, Alberto Camilo Alécio, Maria Virginia Costa Scarpa, Eryvaldo Socrates Tabosa do Egito, Rodrigo Sequinel, Rafael Rodrigues Hatanaka, José Eduardo Oliveira, Anselmo Gomes de Oliveira
The release of MJ from ME systems was evaluated using an apparatus described in the USP Pharmacopeia (Pharmacopeia USP 2000), modified for the spectrophotometer cuvette (Dalmora et al. 2001). The dissolution apparatus, adapted for liquid pharmaceutical drug dosage forms, was set up with the following conditions: dissolution compartment volume 2.5 ml, stirred at 120 rpm, dissolution medium 0.01 M Tris–HCl buffer, pH 7.2 plus sodium lauryl sulfate. Synthetic cellulose acetate membrane (molecular weight cutoff 12,000–14,000 Da) was previously treated with purified water at 100 °C for 5 min and washed with 0.01 M, pH 7.2, Tris–HCl buffer. The membrane was fixed at the end of the glass cylinder of a diffusion cell. The experiment was carried out on formulations A–F described in Table 1, and a MJ micellar solution (Tris–HCl buffer, 20% MJ, and sodium lauryl sulfate) was used as a control. A total of 300 μL from each formulation and control was added separately to the diffusion cells. Every formulation contained 20% of MJ. At regular time intervals, samples of 100 μL were withdrawn from the receptor phase at 2, 4, 6, 8, 10, and 12 h. The in vitro release of each formulation was made in triplicate.
Recent advances in electrospun for drug delivery purpose
Published in Journal of Drug Targeting, 2019
Mengyao Liu, Yanan Zhang, Siyu Sun, Abdur Rauf Khan, Jianbo Ji, Mingshi Yang, Guangxi Zhai
Compared to synthetic polymers, natural polymers have better biocompatibility and low immunogenicity. Some exhibit intrinsic antibacterial properties and better clinical functionalities. There are a lot of natural polymers that have been utilised as electrospun materials like polysaccharides, structural proteins and so on. Chitin, chitosanchitosan (CS), hyaluronic acid (HA) heparin, heparan sulfate (HS), and chondroitin sulfate (ChS) belong to animal polysaccharides. CS has been reported to combat Graffi myeloid tumours and HeLa Cells [5,25]. Cellulose acetate (CA) has a good biocompatibility and can control the release of active pharmaceutical ingredients (APIs). In addition, gelatine manifests good water-solubility and even better surface properties to the materials for cell adhesion, therefore nanofibers incorporated with gelatine exert perfect hydrophilicity and good mechanical property [35]. Different natural polymers have their own merits.
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