Composites of poly(vinyl pyrrolidone)/hydroxyapatite (PVP/HA), at variable proportions (100/0; 80/20; 50/50; 20/80 wt%) were
prepared and characterized by Fourier transformer-infrared spectroscopy (FT-IR), wide angle X-ray diffraction (WAXD), differential
scanning calorimetry (DSC), and thermogravimetry/differential thermogravimetry (TG/DTG). PVP carbonyl stretching was slightly
shifted to lower frequency in composites indicating the formation of hydrogen bonding with HA hydroxyl groups. At the first
cycle of heating, the calorimetric curves revealed a broad peak the intensity of which was reduced insofar as the amount of
PVP decreased in the composites. This peak was attributed to the PVP enthalpy relaxation. According to the TG/DTG curves,
PVP degraded into two steps sharply perceivable in the composites. The first decay was ascribed to the release of the pyrrolidone
pendant groups and the following one concerned the burning of the hydrocarbon chains. The HA molecules seem to exert a catalytic
action on the PVP degradation.
Authors:Ana Rita de Mello Costa, Flávia Silva Marquiafável, Mirela Mara de Oliveira Lima Leite Vaz, Bruno Alves Rocha, Paula Carolina Pires Bueno, Pedro Luiz M Amaral, Hernane da Silva Barud, and Andresa Ap Berreta-Silva
, and efficient delivery system is necessary to assure that the increasing of quercetin solubility be warranted.
The polyvinylpyrrolidone Kollidon ® 25 (PVP K25) is a polymer used to improve the solubility and bioavailability of little soluble
Authors:R. Ambrus, Z. Aigner, L. Catenacci, G. Bettinetti, P. Szabó-Révész, and M. Sorrenti
inclusion complexes of drug with cyclodextrins (CDs) [ 9 – 11 ] are the most frequently employed. In fast-release solid dispersions, a hydrophilic polymer of first choice is polyvinylpyrrolidone (PVP), which is commercially available with various average
Authors:M. I. Loría-Bastarrachea, W. Herrera-Kao, J. V. Cauich-Rodríguez, J. M. Cervantes-Uc, H. Vázquez-Torres, and A. Ávila-Ortega
Poly( N -vinyl-2-pyrrolidone), PVP, has been attracted a great deal of attention in these days as it has been widely used for applications in various fields. This polymer is a synthetically derived vinyl polymer
Authors:Imre Miklós Szilágyi, Eero Santala, Mikko Heikkilä, Marianna Kemell, Timur Nikitin, Leonid Khriachtchev, Markku Räsänen, Mikko Ritala, and Markku Leskelä
Here we present a model study on the heat treatment of electrospun polyvinylpyrrolidone [PVP, (C 6 H 9 NO) n ] and ammonium metatungstate [AMT, (NH 4 ) 6 [H 2 W 12 O 40 ]· n H 2 O] nanofibers. It clearly demonstrates the importance of finding the
Authors:M. Mayo-Pedrosa, C. Alvarez-Lorenzo, and A. Concheiro
The miscibility of poly(N-isopropylacrylamide) (PNIPA) with poly(vinyl pyrrolidone) (PVP) and a cross-linked poly(acrylic
acid) (Carbopol 971P) was evaluated from the rheological data of aqueous dispersions and the temperature of glass transitions of films made
of binary mixtures. PNIPA has a low critical solubility temperature (LCST) of about 33C, below which 1% dispersion behaves
as a viscous system. At temperatures above LCST, the hydrophobic interactions among the isopropyl groups initially provide
transient networks of greater elasticity. The LCST of PNIPA as well as its Tg (144C, estimated by DSC and MTDSC of films) were not modified by the presence of PVP. The immiscibility of PNIPA and PVP
was confirmed by the absence of interaction between both polymers as shown by FTIR analysis of the films. In contrast, PNIPA
and carbopol were miscible and the behaviour of their mixtures differed significantly from that of the parent polymers; i.e.
a strong synergistic effect on the viscoelasticity of the dispersions was observed below the LCST. As temperature increased,
the blends showed a decrease in the loss and storage moduli, especially those with greater PNIPA proportions. The fall was
smoother as the PNIPA proportion decreased. This behaviour may be explained as the result of the balance between PNIPA/carbopol
hydrogen bonding interactions (as shown in the shift of C=O stretch in FTIR spectra) and PNIPA/PNIPA hydrophobic interactions.
The Tg values of the films of the blends showed a positive deviation from the additivity rule; the mixtures containing more than
1:1 amide:carboxylic acid groups have a notably high Tg (up to 181C). This increase is related to the stiffness induced in
the films by the PNIPA/carbopol interactions.
Authors:G. Papageorgiou, A. Docoslis, M. Georgarakis, and D. Bikiaris
In this work, the enhancement of drug dissolution rate through the preparation of new formulations containing Nimodipine in
molecular level dispersion or in nanodispersion into poly(vinyl pyrrolidone) (PVP) matrix, was investigated. Differential
scanning calorimetry (DSC) and modulated-temperature differential scanning calorimetry (MTDSC) in combination with X-ray powder
diffractometry (XRPD) and scanning electron microscopy (SEM) studies showed that Nimodipine was amorphous in solid dispersions
of 10 or 20 mass%, and mainly dispersed on a molecular level. This behaviour is attributed to the strong interactions taking
place between the amine group of Nimodipine and carbonyl group of PVP. At higher drug loadings, crystal reflections in XRPD
patterns and melting peaks of Nimodipine in DSC traces, indicated presence of drug in crystalline form. Micro-Raman studies
in combination with SEM micrographs showed that the mean particle size increases with drug content in the formulations, up
to 10 μm. Moreover, both XRPD patterns and micro-Raman spectra seem to indicate that Nimodipine crystallized in a second,
thermodynamically stable, crystal modification II. The physicochemical characteristics of Nimodipine and the particle size
distribution directly affect the dissolution rate enhancement, which is higher in amorphous dispersions.
Authors:Shinn-Gwo Hong, Tsung-Kai Gau, and Shih-Che Huang
, i.e., the addition of a small amount of tough carboxyl-terminated butadiene acrylonitrile rubber (CTBN) or biocompatible polyvinylpyrrolidone (PVP) polymeric additives, can also result in different changes and improvements of the crystallization and
Authors:T. Shakhtshneider, F. Danède, F. Capet, J. Willart, M. Descamps, S. Myz, E. Boldyreva, and V. Boldyrev
The effect of cryogenic grinding on the piroxicam and its mixtures with polyvinylpyrrolidone (PVP) was studied by powder X-ray
diffraction and differential scanning calorimetry (DSC). The crystallization of the amorphous piroxicam obtained during cryogrinding
showed two events in a DSC curve (noticeable for pure piroxicam, and much more pronounced for the PVP-piroxicam mixtures).
For the same measurement conditions, the intensity ratio of the peaks corresponding to the two events differed for the PVP-piroxicam
mixtures of different drug-excipient ratios. The temperatures, at which these events were observed, increased with the increase
in the PVP-concentration in the mixture. For the mixtures with a high relative content of PVP (≥60%), crystallization was
not observed at all. Only one glass transition was revealed for the mixture containing 80% PVP suggesting that a molecular
alloy was formed.