China
Africa
Explore chapters and articles related to this topic
Application of Bioresponsive Polymers in Drug Delivery
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Manisha Lalan, Deepti Jani, Pratiksha Trivedi, Deepa H. Patel
Pectin is also one of the natural polymers which can gel in nasal fluids. Castile et al. investigated the nasal deposition and gelling properties of PecSys, low methoxy pectin. The clinical utility of pectin in situ gel has been evaluated in trials for the trans-nasal transport of fentanyl, and was similar to the findings of the in vitro models developed by Castile et al. [75]. Pectin extracted from Aloe Vera plant was evaluated as an in situ gelling agent. It was an effective gelling agent at low concentrations of calcium. Advanced studies characterized the gelation process in detail and proved the utility of the system [76, 77].
Injectable Scaffolds for Bone Tissue Repair and Augmentation
Published in Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon, Tissue Engineering Strategies for Organ Regeneration, 2020
Subrata Bandhu Ghosh, Kapender Phogat, Sanchita Bandyopadhyay-Ghosh
In another study, injectable hyaluronic acid (HA)-based hydrogels were developed using cellulose nanocrystals (CNCs) as a reinforcement (Domingues et al. 2015). The injectable hydrogels were composed of adipic acid dihydrazide-modified HA (ADH-HA) and aldehyde-modified HA (a-HA) matrix reinforced with aldehyde-modified CNCs (a-CNCs) (Parameswaran-Thankam et al. 2018, Domingues et al. 2015). The authors reported that the CNCs could initiate both physical cross-linking (through secondary bonding and interactions) and chemical cross-linking (through covalent bonding) with the HA matrix. The resulting nanocomposites were reported to have high storage modulus which could be attributed to a compact network structure assisted by smaller pore dimensions. It was demonstrated that the biocompatibility of HA-CNCs nanocomposites varied with the concentration of CNCs and could be directly correlated with cell viability, metabolic activity and proliferation rate (Domingues et al. 2015). Development of injectable hydrogel nanocomposites based on carboxymethyl cellulose/dextran matrix, reinforced with cellulose nanocrystals (CNCs) and aldehyde-functionalized CNCs (CHO-CNCs) have also been reported (Yang et al. 2013). The researchers reported that the gelation occurred immediately. Unique physical and chemical properties and low cytotoxicity/ecotoxicity of organic cellulose nanocrystals were utilized in such nanocomposites. Besides, the favorable mechanical properties CNCs could make them ideal as load-bearing component in the bone scaffolds.
Closed-Loop Plasmapheresis
Published in James L. MacPherson, Duke O. Kasprisin, Therapeutic Hemapheresis, 2019
Michael J. Lysaght, Walter Samtleben, Baerbel Schmidt, Hans J. Gurland
The pathogens are selectively precipitated or gelled and then filtered across a microporous membrane. Gelation may be prompted by chilling (described below) or by alterations in pH15 or salinity. After the microporous filtration the plasma is returned to its original temperature or ionic milieu (usually by dialysis). Although more selective than cascade filtration, these approaches are not highly specific for individual classes of pathogens. The method based upon chilling is fully commercial and referred to as cryofiltration.
Unification of medicines and excipients: The roles of natural excipients for promoting drug delivery
Published in Expert Opinion on Drug Delivery, 2023
Minfang Feng, Xingxing Dai, Cuiting Yang, Yingying Zhang, Yuting Tian, Qingsong Qu, Mengke Sheng, Zhixun Li, Xinhui Peng, Shuai Cen, Xinyuan Shi
The gel is a three-dimensional network structure formed by cross-linking polymers or colloidal particles with a linear structure through chemical bonds between molecules (including intra-molecular and extra-molecular interactions). The types of chemical bonds are based on their structures and properties. The occurrence of gelation can be affected by temperature, solution pH, ions, etc. So, the gelation of solutes can be triggered by changing temperature or other influencing factors. For the gelation of polysaccharide molecules in water, the polysaccharides are associated with each other through chemical bonds. And they stabilize the water molecules around them by hydrogen bonds between water molecules and polysaccharides and lead to hydrogen bonds between water molecules and water molecules, which results in gelation [225–227]. Polysaccharides in herbal medicine frequently crosslink with polymer by the effect of crosslinkers like Psyllium polysaccharide, Bletilla striata polysaccharide, Tremella polysaccharide, etc. The forming mechanism of Psyllium polysaccharide-based hydrogel is shown in Figure 6. Firstly, trigger the propagation of Psyllium polysaccharide, acrylamide(AAm), and methacrylamide(MAAm). Then, Psyllium polysaccharide, AAm/MAAm polymer, was generated. Last, a three-dimensional network was formed after adding a crosslinker(N, N’-methylenebisacrtlamide) crosslinked the AAm/MAAm polymer and Psyllium polysaccharide.
Application of HPMC HME polymer as hot melt extrusion carrier in carbamazepine solid dispersion
Published in Drug Development and Industrial Pharmacy, 2020
Hao Wu, Yanhong Liu, Tianyuan Ci, Xue Ke
HME mostly uses high-temperature-resistant polymer as carriers [3], which are stable even at high temperatures, which is benefit for the improving the dispersion state of drugs and avoiding the recrystallization of drug. Among these, the hydrophilic polymer can also improve the wettability during dissolution, and thus have become one of the important choices for insoluble drugs to increase dissolution [4]. Unfortunately, the extrudate’s agglomeration usually appears in dissolution due to the high viscosity of polymers for the hydrophilic polymer would become sticky after contacting with water [5]. And this gelatination phenomenon would further resist water infiltrating into the interior of the preparation, leading to the poor disintegration of the preparation and the dissolution of the active component. And this situation could only be alleviated after the gelation gradually disappeared. For fast or immediate release solid dispersions, this situation may not only lead to unacceptable dissolution behaviors, but also impede the advantages of HME in solubilization.
Organogels based on amino acid derivatives and their optimization for drug release using response surface methodology
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Beibei Hu, Haipeng Yan, Yanping Sun, Xi Chen, Yujuan Sun, Sanming Li, Yongshuai Jing, Heran Li
However, the addition of the antigelation solvent bring some problems in the meanwhile, such as the initial burst of drugs and unclear degradation mechanism of the organogels. As the diffusion rate and dosage volume affect the diffusion time of the antigelation solvent, the uncontrollable drug release before the drug depot formed severely restricted its further application. For the most drugs with a narrow therapeutic window, the burst release can lead to a different degree of toxicity and side effects. The solution to these problems focussed on two aspects. One is shrinking the gelation time after administration, such as increasing the gelator concentration, modifying gelator structure or adding crosslinker [24–26]. The other is preloaded the drug into some vesicles such as microemulsions, nanoparticles or microspheres [27,28]. Then these drug vesicles were loaded into gels to achieve the sustained release aim and avoid the burst release. While this form of preparation tremendously increases the difficulty in research and preparation development, especially in the large-scale manufacture process. Because the preparation process is complex and drug-specific, it is necessary to design appropriate new preparations for specific drugs. Thus it is more feasible to explore the properties of each component in the gel system in analyzing the burst release.