Polymers hydroxypropyl cellulose

Nakamura et al. ° studied the adhesion of water-soluble and neutral polymers, hydroxypropyl cellulose (HPC), xanthan gum (XG), tamarind gum (TG), and polyvinyl alcohol (PVA) to nasal mucosa in vitro and in vivo. The polymers, mixed with a dye, were applied as powders to the nasal cavity of rabbits, and the remaining dye residue was determined at 2, 4, and 6 h after nasal instillation with a thin fiberscope. The polymer XG showed the longest residence time of the dye in the cavity, followed by TG, HPC, and PVA in decreasing order. For the mixture XG and XG-PVA (2 8), some residue of dye could still be observed 6h after administration. The order of adhesion of these polymers to agar plates in vitro agreed with that of their mucoadhesion in vivo. Ilium et al. introduced bioadhesive microspheres for nasal delivery of poorly absorbable drugs. Radiolabelled microspheres made from diethylaminoethyl (DEAE)-dextran, starch microspheres, and albumin microspheres were administered to human volunteers and appeared to be cleared significantly slower than solutions or... 

It has been shown that a semirigid-chain polymer, hydroxypropyl cellulose with M = 60,000, turns into a LC melt at 160-205 C, characterized by the presence of a creep limit, like other melts and solutions of LC polymers. However, the fibers formed from such a melt have weak molecular orientation and low strength [58]. 

Dispersion polymerization involves an initially homogeneous system of monomer, organic solvent, initiator, and particle stabilizer (usually uncharged polymers such as poly(A-vinyl-pyrrolidinone) and hydroxypropyl cellulose). The system becomes heterogeneous on polymerization because the polymer is insoluble in the solvent. Polymer particles are stabilized by adsorption of the particle stabilizer [Yasuda et al., 2001], Polymerization proceeds in the polymer particles as they absorb monomer from the continuous phase. Dispersion polymerization usually yields polymer particles with sizes in between those obtained by emulsion and suspension polymerizations—about 1-10 pm in diameter. For the larger particle sizes, the reaction characteristics are the same as in suspension polymerization. For the smallest particle sizes, suspension polymerization may exhibit the compartmentalized kinetics of emulsion polymerization. 

Nowadays, the sieving matrices most employed in CSE are polymer solutions that under suitable conditions may form a transient mesh or sieving matrix that provide the size-based separation of charged biopolymers. The polymer solutions can be formulated with linear acrylamide and N-substituted acrylamide polymers, cellulose derivatives, polyethylene oxide, and its copolymers or with a variety of polymers, such as polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), and hydroxypropyl cellulose(HPC), which do not necessitate the preventive coating of the capillary wall due to their ability to dynamically coat the inner surface of the capillary, resulting in suppressed EOE and sample interactions with the capillary wall. 

Fig. 7. Comparison of experimental phase boundary concentrations between the isotropic and biphasic regions for various liquid-crystalline polymer solutions with the scaled particle theory for wormlike hard spherocylinders. ( ) schizophyllan water [65] (A) poly y-benzyl L-glutamate) (PBLG)-dimethylformamide (DMF) [66-69] (A) PBLG-m-cresoI [70] ( ) PBLG-dioxane [71] (O) PBLG-methylene chloride [71] (o) po y(n-hexyl isocyanate) (PHICH°Iuene at 10,25,30,40 °C [64] (O) PHIC-dichloromethane (DCM) at 20 °C [64] (5) a po y(yne)-platinum polymer (PYPt)-tuchIoroethane (TCE) [33] ( ) (hydroxypropyl)-cellulose (HPC)-water [34] ( ) HPC-dimethylacetamide (DMAc) [34] (N) (acetoxypropyl) cellulose (APC)-dibutylphthalate (DBP) [35] ( ) cellulose triacetate (CTA)-trifluoroacetic acid [72]...

Polymeric steric stabilizer such as poly(vinylpyrrolidone) (PVPo),poly(acrylic acid), poly(hydroxypropyl)cellulose, etc., are used to prepare monodisperse polymer in dispersion polymerization of monomers such as alkyl acrylates and methacrylates, and styrene in polar media. AB and ABA block copolymers are a second type of steric stabilizer which can be used in dispersion polymerization. For example, the poly(styrene-h-ethylene oxide) was recently used by Winnik et al. [6] in the dispersion polymerization of styrene in methanol. 

Liquid-crystalline solutions and melts of cellulosic polymers are often colored due to the selective reflection of visible fight, originating from the cholesteric helical periodicity. As a typical example, hydroxypropyl cellulose (HPC) is known to exhibit this optical property in aqueous solutions at polymer concentrations of 50-70 wt%. The aqueous solution system is also known to show an LCST-type of phase diagram and therefore becomes turbid at an elevated temperature [184]. 

The mechanism of separation with linear polymers is as follows. At a certain polymer concentration known as the entanglement threshold, the individual polymer strands begin to interact with each other, leading to a meshlike structure within the capillary. This allows DNA separation to take place. Many of the common polymers are cellulose derivatives, such as hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and methylcellulose. Other applicable polymers include linear polyacrylamide, polyethylene oxide, agarose, polyvinyl pyrrolidone, and poly-N. Ar-dimethylacrylamide. High-resolution separation up to 12,000 bp has been reported using entangled polymer solutions. 

Research on nasal powder drug delivery has employed polymers such as starch, dextrans, polyacrylic acid derivatives (e.g., carbopol, polycarbophil), cellulose derivatives (microcrystalline cellulose, semicrystalline cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose), chitosan, sodium alginate, hyaluronans, and polyanhydrides such as poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA). Many of these polymers have already been used as excipients in pharmaceutical formulations and are often referred to as first-generation bioadhesives [38-45], In nasal dry powder a single bioadhesive polymer or a... 

During dispersion polymerization polymer particles are formed from an initially homogeneous reaction mixture by polymerization in the presence of a polymeric steric stabilizer. The process is applicable to monomers which yield polymers that are insoluble in a solvent for the monomer. Styrene has been polymerized in alcohols, with steric stabilizers such as poly(A -vinylpyrrolidone) (see Fig. 1-4 for monomer structure) or hydroxypropyl cellulose. Hydrocarbon... 

A review of vaginal bioadhesive formulations indicates that bioadhesive tablets have been used for localized treatment of diseases in the vaginal tissue.F ° l For example. Bleomycin, an antitumor agent, was incorporated into a flat-faced disk fabricated from a combination of hydroxypropyl cellulose and poly-(acrylic acid) (Carbopol 934). ° The tablet was designed to release Bleomycin at a slow rate to minimize irritation to healthy mucosa. Another vaginal tablet is formulated from the combination of poly(acrylic acid) with hydroxypropyl methylcellulose and ethylcellu-lose. Other polymer combinations evaluated for potential bioadhesive vaginal delivery include poly(acrylic acid) and sodium carboxymethyl cellulose with Avicel PH102 (methylcellulose) as the diluent. Insulin has been formulated in a cross-linked poly(acrylic acid) gel... 

Among the polymers used in lens comfort solutions are polyvinyl alcohol, polyvinylpyrrolidone, dextran, and various cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methylcellulose. Surfactants include certain poloxamer and poloxamine compounds. Other normal components comprise appropriate preservative(s) as well as buffering and tonicity-adjusting agents. 

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