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-term consequence of PVP in the treatment of metastatic damages of different tumors in the spine, and it has been expanded as an interventional technique to treat spinal osteolytic destruction, multiple myeloma, and painful vertebral compression fractures of

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]. Several agents have been suggested by the literature; nevertheless, citric acid, chlorhexidine (CHX) and povidone-iodine (PVP-iodine) are probably the most often discussed ones [ 24, 25 ]. The objective of our study was to compare the decontaminating

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Grinding of drugs with pharmaceutical excipients at cryogenic temperatures

Part I. Cryogenic grinding of piroxicam-polyvinylpyrrolidone mixtures

Journal of Thermal Analysis and Calorimetry
Authors: T. Shakhtshneider, F. Danède, F. Capet, J. Willart, M. Descamps, S. Myz, E. Boldyreva, and V. Boldyrev

Abstract  

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.

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Orvosi Hetilap
Authors: Zsolt Kulcsár, Miklós Marosfői, Zsolt Berentei, Róbert Veres, István Nyáry, and István Szikora

Háttér és célkitűzés: A percutan vertebroplastica (PVP) rendkívül hatékony módszer az osteoporoticus csigolyatörések okozta fájdalom csökkentésében. A beavatkozás után azonban a betegek egy része újabb kompressziós törést szenved. A vizsgálat célja az újabb törések gyakoriságának felmérése, valamint a PVP okozati szerepének becslése volt a kezelt betegcsoportban. Betegek és módszer: A retrospektív vizsgálatban áttekintettük az 5 és fél év alatt, csontritkulás talaján csigolyatörést szenvedett és PVP-vel kezelt, egymást követő betegek adatait. A vizsgálati csoportot a teljes populáció azon tagjai alkották, akik a csigolyastabilizáció után újabb törést szenvedtek. A vizsgálat elsődleges végpontja a PVP után kialakult újabb törések előfordulásának gyakorisága volt. A másodlagos végpontot a korábban kezelt csigolyákkal szomszédos szegmentumokban, 90 napon belül kialakult újabb törések képezték, ugyanis ebben a csoportban feltételezhető leginkább a PVP biomechanikai kiváltó szerepe. Eredmények: Összesen 396 beteget kezeltünk PVP-vel osteoporoticus csigolyatörés miatt. Az átlagéletkor 68±11 év volt. A betegek 77%-a nő. Összesen 73 beteg szenvedett a PVP után újabb törést (vizsgálati csoport), amely a teljes populáció 18,4%-át képezte. Ebben a csoportban egy főre átlagosan 3,8 csigolyatörés jutott. A PVP-vel szomszédos törések szignifikánsan gyakrabban fordultak elő, mint a távoli szegmentumot érintő fracturák. Összesen 44 beteg szenvedett szomszédos csigolyatörést a PVP utáni 90 napon belül, ők a teljes populáció 11%-át képviselték. A teljes populációhoz viszonyítva ebben a csoportban szignifikánsan kevesebb volt a férfi. Következtetés: PVP után közel minden ötödik betegnek van arra esélye, hogy újabb törést szenvedjen, azonban a korábban elvégzett csigolyastabilizációnak valószínűleg csak minden tizedik betegnél lesznek biomechanikai következményei, egy újabb fractura formájában. A legnagyobb kockázatúak a több törést szenvedett, súlyos csontritkulásban szenvedő nőbetegek.

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Abstract  

In the present study PVP/HPMC and PVP/Chitosan polymer blends were prepared by using the solvent evaporation technique. From DSC studies were revealed that both blends are completed miscible in the entire composition range since only one glass transition temperature was detected. Miscibility can be attributed to the strong interactions evolved between the carbonyl group of PVP, which acts as strong proton acceptor, with hydroxyl and amino-groups of HPMC and Chitosan, which are proton donors. Thus hydrogen bonds are easily formed, as was verified by FTIR, producing miscible blends. However, the extent of interactions depends from polymer composition and mainly from the ratio and the kind of reactive groups. In PVP/HPMC blends a negative variation of T g is recorded while in PVP/Chitosan the variation has a sigma form. The miscibility of these systems creates matrixes with completely different physical properties in order to use as effective drug carriers. PVP/HPMC blends can be used as pulsatile chronotherapeutics systems adjusting exactly the time of the drug release while PVP/Chitosan blends can be used to control the release profile of a poorly water soluble drug. In these blends HPMC and Chitosan respectively are the control factors for the corresponding applications.

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Grinding of drugs with pharmaceutical excipients at cryogenic temperatures

Part II. Cryogenic grinding of indomethacin-polyvinylpyrrolidone mixtures

Journal of Thermal Analysis and Calorimetry
Authors: T. Shakhtshneider, F. Danède, F. Capet, J. Willart, M. Descamps, L. Paccou, E. Surov, E. Boldyreva, and V. Boldyrev

Abstract  

The effect of cryogenic grinding on the indomethacin (IMC) and its mixtures with polyvinylpyrrolidone (PVP) was studied by powder X-ray diffraction and differential scanning calorimetry. Cryoground mixtures were shown to form glass solutions. PVP inhibits the crystallization of IMC from the amorphous state: the crystallization temperature of IMC in the mixtures with PVP increases, and the amorphous state is preserved longer on storage. The mixtures were characterized by Raman spectroscopy. Dissolution of the IMC in the cryoground mixtures is higher as compared to the pure form, also after a prolonged storage.

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Abstract  

The physical stability of amorphous drug in solid dispersion was estimated using differential scanning calorimetry (DSC). Tolbutamide (TB) and flurbiprofen (FBP) were selected as insoluble drugs in water. Polyvinylpyrrolidone (PVP) was selected as a polymer for solid dispersion. Solid dispersions of various ratios of TB or FBP and PVP-K25 were prepared by solvent evaporation method and the induction period of crystallization from amorphous drug in solid dispersion was measured by DSC. Compared with FBP, the induction period of crystallization from TB was delayed by an addition of PVP. The improvement of the physical stability by the addition of PVP-K25 was estimated from the activation energy of diffusion of drug molecules and the interfacial free energy between drug crystal and supercooled liquid of drug in solid dispersion. From thses results, the hindrance of the diffusivity of the drug molecule might be mainly affected the delay of the induction period of crystallization of TB and FBP.

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Abstract  

No-carrier-added (nca) 199–201Tl has been separated from nca 199–201Pb using an environmentally friendly biocompatible polymer, poly(N-vinylpyrrolidone). The method uses no harmful chemicals and is based on the process of dialysis of PVP-Pb and PVP-Tl complexes against triple-distilled water. It has been observed after one hour of dialysis that 75–85% Tl (in both +3 and +1 oxidation states) comes out of dialysis sack without any contamination from lead.

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Abstract  

Purposes of this paper were to prepare and study new drug delivery systems for both flavanone glycosides and their aglycones based on solid-dispersion systems. These compounds are poor water soluble drugs, so an enhancement of their dissolution is a high priority. Solid-dispersion systems were prepared using PVP, PEG and mannitol as drug carrier matrices. Characterizations of these dispersions were done by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The glass transition (T g) temperature of PVP was only recorded in the DSC thermograms of PVP solid-dispersions of both flavanone glycosides and their aglycones, while in case of PEG and mannitol solid-dispersions endotherms of both glycosides and aglycones were noticed with low peak intensity, indicating that high percent of drug is in amorphous state. The XRD patterns of all PVP solid-dispersions of aglycones show typical amorphous materials, but XRD patterns of their glycosides reveal the presence of crystalline material. However, in all solid dispersions shifts in T g of PVP as well as T m of PEG were observed, indicating the existence of some interactions between drugs and matrices. SEM and TEM microscopy revealed that PVP/aglycone flavanone compounds are nanodispersed systems while all the other solid dispersions are microcrystalline dispersions. The solubility of both flavanone glycosides and their aglycones was directly affected by the new physical state of solid dispersions. Due to the amorphous drug state or nano-dispersions in PVP matrices, the solubility was enhanced and found to be 100% at pH 6.8 in the nano-dispersion containing 20 mass% of aglycones. Also solubility enhancement was occurred in solid dispersions of PEG and mannitol, but it was lower than that of PVP nano-dispersions due to the presence of the drug compounds in crystalline state in both matrices.

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Summary  

Solid dispersions were prepared to enhance the dissolution rate of rofecoxib. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used for the characterization of solid dispersions of polyvinyl pyrrolidone (PVP):talc:drug (3:1:1) and hydroxypropyl methylcellulose (HPMC):talc:drug (4:1:1). The DSC study indicated that PVP solid dispersion showed formation of fusion solution while HPMC solid dispersion showed no intermolecular fusion during the preparation of solid dispersions by spray dry process. The dissolution profiles and the calculated times for 75 and 90% drug release showed that dissolution rate of rofecoxib was improved in solid dispersions as compared to pure drug and physical mixtures. The DSC and XRD were successfully employed to find out the crystalline state of drug in the both solid dispersions. PVP solid dispersion gave better dissolution rate than HPMC solid dispersion. The drug was transformed from crystalline to amorphous form in PVP solid dispersion which was further conformed by XRD and DSC. The PVP:talc:drug solid dispersion can be used for the dissolution enhancement and thereby bioavailability of rofecoxib.

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