Polyvinylpyrrolidone system

MacKenzie, A. P., Rasmussen, D. H. Interactions in the water-polyvinylpyrrolidone system at low temperatures, In Jellinek, H. H. G. ed. Water Structure at the Water-Polymer Interface. New York Plenum Publishing, 1972, pp. 146-172. 

Fini, A., Holgado, M., Rodriguez, L., and Cavallari, C., Ultrasound-compacted indomethacin/polyvinylpyrrolidone systems Effect of compaction process on particle morphology and dissolution behavior, Journal of Pharmaceutical Sciences, Vol. 91, No. 8, 2002, pp. 1880—1890. 

The poly(methacrylic acid)-polyvinylpyrrolidone system have been studied in detail in the series of the homopolymer complexes investigated by the authors (Table 2). The possibility of complex formation in this system has been shown by potentiometry, conductometry and viscometry and also by IR spectroscopic and thermogravimetric investigations of PMAA-PVP complexes in the solid state27,57). 

Corrigan OI, Holohan EM. Amorphous spray-dried hydroflumethiazide-polyvinylpyrrolidone systems physicochemical properties. J Pharm Pharmacol 1984 36 217-221. 

Polyvinylpyrrolidone (PVP) is water-soluble polymer, whieh is widely used in various industries and agrieulture beeause of high inelination to the eomplex formation and eapaeity to stabilization of different systems. 

Ffirai and Toshima have published several reports on the synthesis of transition-metal nanoparticles by alcoholic reduction of metal salts in the presence of a polymer such as polyvinylalcohol (PVA) or polyvinylpyrrolidone (PVP). This simple and reproducible process can be applied for the preparation of monometallic [32, 33] or bimetallic [34—39] nanoparticles. In this series of articles, the nanoparticles are characterized by different techniques such as transmission electronic microscopy (TEM), UV-visible spectroscopy, electron diffraction (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) or extended X-ray absorption fine structure (EXAFS, bimetallic systems). The great majority of the particles have a uniform size between 1 and 3 nm. These nanomaterials are efficient catalysts for olefin or diene hydrogenation under mild conditions (30°C, Ph2 = 1 bar)- In the case of bimetallic catalysts, the catalytic activity was seen to depend on their metal composition, and this may also have an influence on the selectivity of the partial hydrogenation of dienes. 

Bell et al. (2002) investigated the relationship between water mobility as measured by oxygen-17 NMR (transverse relaxation rate obtained from linewidth at half-height) and chemical stability in glassy and rubbery polyvinylpyrrolidone (PVP) systems. Reported results suggest that water mobility in PVP model systems was not related to Tg. The study did not find a link between water mobility and reaction kinetics data (half-lives) for degradation of aspartame, loss of thiamin and glycine, and stability of invertase. 

An interesting feature of current commercial products is that the polymer vehicles available for formulation have been limited to nonionic and anionic materials. The delivery vehicles available included off-the-shelf polymers such as carboxymethylcellulose, soluble starch, hydroxyethyl-cellulose, polyvinyl alcohol, poly(acrylic acid), and polyvinylpyrrolidone, or mixtures thereof. The choice of available polymeric delivery system primarily depends on component compatibility, aesthetics, and efficacy. However, by reliance upon available (off-the-shelf) systems, limitations on bioadhesion, drug bioavailability, contraceptive efficacy, and end-use characteristics has been limited. 

The 24 hour salt fog corrosion resistance for the photocured B210/NVP and B210/GBL systems were vastly different. Using NVP as a diluent, SOX rusting of the sample was seen, while the GBL diluent showed no rusting. This difference is attributed to the inherent water solubility of polyvinylpyrrolidone (19). 

To study the nature of this rapid polymer transport in detail, this section will be concerned with a series of experimental measurements on one particular system, namely a solution of dextran T10 (N5W 10 ) with a uniform concentration of 135 kg m-3 and an imposed gradient of a linear, flexible polyvinylpyrrolidone) (NTn 3 x 10s) (PVP 360). This gradient initially extended from 5 kg m3 to zero concentration. The choice of using the polymers at this concentration was based upon our earlier work441 in which it was shown that nearly maximal transport rates of PVP 360 occur in such a system. This system will be referred to as the standard system. The phase diagram of this PVP 360/dextran T10 mixture clearly demonstrates that the transport experiments were performed within the one-phase region 47). 

Abbreviations. PEG, polyethylene glycol PVP, polyvinylpyrrolidone PVA, polyvinylalcohol HPMC, hydroxypropylmethylcellulose CMEC, carboxymethylethylcellulose, BCS, biopharmaceutical classification system Y, Yes. 

In relation to enzymic cytochrome P-450 oxidations, catalysis by iron porphyrins has inspired many recent studies.659 663 The use of C6F5IO as oxidant and Fe(TDCPP)Cl as catalyst has resulted in a major improvement in both the yields and the turnover numbers of the epoxidation of alkenes. 59 The Michaelis-Menten kinetic rate, the higher reactivity of alkyl-substituted alkenes compared to that of aryl-substituted alkenes, and the strong inhibition by norbornene in competitive epoxidations suggested that the mechanism shown in Scheme 13 is heterolytic and presumably involves the reversible formation of a four-mernbered Fev-oxametallacyclobutane intermediate.660 Picket-fence porphyrin (TPiVPP)FeCl-imidazole, 02 and [H2+colloidal Pt supported on polyvinylpyrrolidone)] act as an artificial P-450 system in the epoxidation of alkenes.663... 

Similar grafting experiments by the emulsion technique were described (34) in the system vinyl chloride/copolymer butyl methacrylate-methacrylic acid and in the reverse system, and also in the system styrene/polyvinyl chloride. In this last case again as in homogenous medium, the inverse process failed (vinyl chloride on polystyrene). Grafted acrylonitrile copolymers were also prepared in order to improve their dyeability, by polymerizing acrylonitrile in emulsion in the presence of many different polymers as polyvinyl alcohol, polymethacrylamide and polyvinylpyrrolidone (119, 120, 121), polyvinyl acetate and polyacrylic acid (115), wool (224,225), proteins (136), etc. 

The irradiation of a mixture of two polymers A and Bn, either in the solid state or in solution, yields free radicals A and Z , which by recombination give the initial An and Bn polymers or by cross-addition a graft (or block) copolymer 4j,BQ. Although this method gives only very low yields of graft copolymers, it has nevertheless be applied by Hekg-lein in the system polyvinylpyrrolidone-polyacrylamide (102). 

The gels can incorporate even polymers such as, for example, water-soluble polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), and polypropyl-eneglycol (PPG). For the PE0/V205 system the interlayer broadening achieved 13.2 A, which corresponds to more probable placement of the polymer molecules along the layers [1373] (Fig. 11.1 b). 

Three classes of PSAs used most widely in transdermal systems are polyisobutylene (PIB), polyacrylate, and polydimethylsiloxane (silicone). More recently, hydrophilic adhesive compositions, hydrogels composed of high-molecular-weight polyvinylpyrrolidon (PVP) and oligometric polyethylene oxide (PEO), have been shown to be compatible with a broad range of drugs and are used in several commercial products.60... 

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