The Influence of Thermal and Mechanical Preparative Techniques on the Amorphous State of Four Poorly Soluble Compounds

2005 ◽  
Vol 94 (9) ◽  
pp. 1998-2012 ◽  
Author(s):  
James E. Patterson ◽  
Michael B. James ◽  
Angus H. Forster ◽  
Robert W. Lancaster ◽  
James M. Butler ◽  
...  
Keyword(s):  
Amorphous State ◽  
Poorly Soluble

scholarly journals Microspherical Particles of Solid Dispersion of Polyvinylpyrrolidone K29-32 for Inhalation Administration

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
L. S. Usmanova ◽  
M. A. Ziganshin ◽  
I. T. Rakipov ◽  
N. M. Lyadov ◽  
A. E. Klimovitskii ◽  
...  
Keyword(s):  
Spray Drying ◽  
Solid Dispersions ◽  
Amorphous State ◽  
Optimal Size ◽  
Drying Process ◽  
Promising Alternative ◽  
Poorly Soluble ◽  
Model Drug ◽  
Pharmaceutical Properties ◽  
Inhalation Administration

Inhalation administration is a promising alternative to the invasive drug delivery methods. The particle size required for ideal drug aerosol preparation is between 1 and 3 μm. The application of microspherical particles of solid dispersions enhances bioavailability of poorly soluble drugs due to the solubilization. In the present work, the spray drying process of the production of microspherical particles of solid dispersions of polyvinylpyrrolidone K29-32 with model hydrophobic drug, phenacetin, was optimized using the results of DSC, PXRD, and viscometry. The diameter of the obtained particles is within 1–3 μm range. The Gibbs energy of dissolution in water was shown to be negative for the mixture with polymer/phenacetin mass ratio 5 : 1. We have demonstrated that the optimal size distribution for the inhalation administration is obtained for microspherical particles produced using spray caps with 7.0 μm hole size. The dissolution rates of phenacetin from the produced microspherical particles were faster than that of drug powder. As evidenced by powder X-ray diffraction data, phenacetin stayed in amorphous state for 4 months in microspherical particles of solid dispersions. According to the obtained results, strategic application of the spray drying process could be beneficial for the improvement of the pharmaceutical properties of model drug, phenacetin.

scholarly journals Enhanced Dissolution Efficiency of Tamoxifen Combined with Methacrylate Copolymers in Amorphous Solid Dispersions

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1046
Author(s):  
Dayanne T. C. da Silva ◽  
Daniela Nadvorny ◽  
Lucas J. de A. Danda ◽  
Amanda C. Q. de M. Vieira ◽  
Patricia Severino ◽  
...  
Keyword(s):  
Drug Loading ◽  
Solid Dispersions ◽  
Amorphous State ◽  
Amorphous Solid ◽  
Physical Mixture ◽  
Polymer Mixture ◽  
Scanning Calorimetry ◽  
Amorphous Solid Dispersions ◽  
Acrylate Copolymer ◽  
Poorly Soluble

Amorphous solid dispersions (SDs) containing poorly soluble tamoxifen dispersed in a meth(acrylate) copolymer combination were proposed as a controlled release system. The objective of this work was to investigate the characteristics and performance of the tamoxifen–polymer mixture and evaluate the changes in functionality through a supersaturating dissolution study condition while comparing it to a physical mixture at a fixed drug-loading proportion. Two polymers, Eudragit® L 100 and Eudragit® RL 100, were used to prepare SDs with a 1:1 polymer ratio, containing 10%, 20%, or 30% (wt/wt%) of tamoxifen, by the solvent evaporation method. A physical mixture containing 30% of tamoxifen was also prepared for comparison. SDs were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. Dissolution tests were conducted under non-sink conditions to verify the occurrence of drug recrystallization upon its release. Solid-state characterizations confirmed that the drug was in the amorphous state within the polymeric matrix. Tamoxifen release in an acidic medium was mainly affected by the increase in drug concentration caused by the possible loss of interactions that characterize the main polymer functionalities. At pH 7.4, supersaturation was slowly achieved while also contributing to the increase in the kinetic solubility of the drug. The physical mixture demonstrated the best overall performance, suggesting that the polymeric interactions may have negatively affected the drug release. The combination of polymers in the composing SD proved to be a promising strategy to tailor the delivery of poorly soluble drugs. Our study highlights important information on the behavior of tamoxifen as a poorly soluble drug in supersaturating dissolution conditions while released from SD systems.

Porous calcium carbonate as a carrier material to increase the dissolution rate of poorly soluble flavouring compounds

2017 ◽  
Vol 8 (4) ◽  
pp. 1627-1640 ◽  
Author(s):  
Maria Lundin Johnson ◽  
David Noreland ◽  
Patrick Gane ◽  
Joachim Schoelkopf ◽  
Cathy Ridgway ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Dissolution Rate ◽  
Amorphous State ◽  
Carrier Material ◽  
Enhanced Dissolution ◽  
Poorly Soluble ◽  
Porous Calcium Carbonate

Flavouring molecules stabilised in amorphous state when loaded in FCC show enhanced dissolution rate compared to the crystalline counterpart.

scholarly journals The Enhancement the Solubility and the Dissolution Rate of Rebamipide by Solid Dispersion Technique

2018 ◽  
pp. 55-65
Author(s):  
Muna Yehia Ismail ◽  
Mowafaq M. Ghareeb
Keyword(s):  
Solid Dispersion ◽  
Drug Carrier ◽  
Amorphous State ◽  
Solvent Evaporation ◽  
Dispersion Matrix ◽  
X Ray Diffraction ◽  
Preparation Methods ◽  
Poorly Soluble ◽  
Dispersion Technique ◽  
Drug Polymer Interaction

Solid dispersion is an attractive tool of pharmaceutical technology used to improve the physical properties of drugs. Among these properties is to enhance the solubility of the drugs.Rebamipide is a poorly soluble drug of class IV of biopharmaceutical classification system (BCS).Rebamipide is used as potent antiulcer, mucoprotective drug, by stimulating the generation of prostoglandine enhanced mucosal protection.Rebamipide was formulated as a solid dispersion using different polymers such as pluronic F-127, PEG6000, PVP K30, and TPGS by using different preparation methods solvent evaporation, fusion, and kneading methods.It was seen that rebamipide was successfully dispersed in a homogenous solid dispersion matrix by solvent evaporation method using TPGS (1:15) drug carrier ratio.Moreover, the results revealed that the solubility of rebamipide (23.9µg/ml) increased significantly (p?0.05) by 36.4 x fold to obtain 874µg/ml solubility in rebamipide matrix. On the other hand, characterization of rebamipide solid dispersion using FTIR, DSC, SEM and x-ray diffraction demonstrated no drug polymer interaction, and converting the rebamipide from crystal to amorphous state lattice.  

Role of boundaries in the crystallization of amorphous films

1988 ◽  
Vol 46 ◽  
pp. 626-627
Author(s):  
D. A. Smith
Keyword(s):  
Low Temperature ◽  
Amorphous State ◽  
Nucleation And Growth ◽  
Amorphous Films ◽  
Island Nucleation ◽  
Surface Steps ◽  
Transmission Electron ◽  
Component Systems ◽  
Temperature Deposition

The nucleation and growth processes which lead to the formation of a thin film are particularly amenable to investigation by transmission electron microscopy either in situ or subsequent to deposition. In situ studies have enabled the observation of island nucleation and growth, together with addition of atoms to surface steps. This paper is concerned with post-deposition crystallization of amorphous alloys. It will be argued that the processes occurring during low temperature deposition of one component systems are related but the evidence is mainly indirect. Amorphous films result when the deposition conditions such as low temperature or the presence of impurities (intentional or unintentional) preclude the atomic mobility necessary for crystallization. Representative examples of this behavior are CVD silicon grown below about 670°C, metalloids, such as antimony deposited at room temperature, binary alloys or compounds such as Cu-Ag or Cr O2, respectively. Elemental metals are not stable in the amorphous state.

Structures and crystallization of vacuum-deposited amorphous Se and Sb films

1990 ◽  
Vol 48 (4) ◽  
pp. 140-141
Author(s):  
Makoto Shiojiri ◽  
Toshiyuki Isshiki ◽  
Tetsuya Fudaba ◽  
Yoshihiro Hirota
Keyword(s):  
Monte Carlo ◽  
Electron Microscope ◽  
Monte Carlo Method ◽  
Computer Program ◽  
Radial Distribution ◽  
Film Formation ◽  
Amorphous State ◽  
Two Dimensional ◽  
Amorphous Films ◽  
Binding Condition

In hexagonal Se crystal each atom is covalently bound to two others to form an endless spiral chain, and in Sb crystal each atom to three others to form an extended puckered sheet. Such chains and sheets may be regarded as one- and two- dimensional molecules, respectively. In this paper we investigate the structures in amorphous state of these elements and the crystallization.HRTEM and ED images of vacuum-deposited amorphous Se and Sb films were taken with a JEM-200CX electron microscope (Cs=1.2 mm). The structure models of amorphous films were constructed on a computer by Monte Carlo method. Generated atoms were subsequently deposited on a space of 2 nm×2 nm as they fulfiled the binding condition, to form a film 5 nm thick (Fig. 1a-1c). An improvement on a previous computer program has been made as to realize the actual film formation. Radial distribution fuction (RDF) curves, ED intensities and HRTEM images for the constructed structure models were calculated, and compared with the observed ones.

Microstructure of YBa2Cu3O7-x thin films deposited by dc sputtering

1989 ◽  
Vol 47 ◽  
pp. 172-173
Author(s):  
O. Eibl ◽  
G. Gieres ◽  
H. Behner
Keyword(s):  
Thin Films ◽  
Cross Sections ◽  
Intermediate Layer ◽  
Amorphous State ◽  
Critical Currents ◽  
Dc Sputtering ◽  
State Process ◽  
Diffraction Patterns ◽  
Film Substrate ◽  
Substrate Temperatures

The microstructure of high-Tc YBa2Cu3O7-X thin films deposited by DC-sputtering on SrTiO3 substrates was analysed by TEM. Films were either (i) deposited in the amorphous state at substrate temperatures < 450°C and crystallised by a heat treatment at 900°C (process 1) or (ii) deposited at around 740°C in the crystalline state (process 2). Cross sections were prepared for TEM analyses and are especially useful for studying film substrate interdiffusion (fig.1). Films deposited in process 1 were polycristalline and the grain size was approximately 200 nm. Films were porous and the size of voids was approximately 100 nm. Between the SrTiO3 substrate and the YBa2Cu3Ox film a densly grown crystalline intermediate layer approximately 150 nm thick covered the SrTiO3 substrate. EDX microanalyses showed that the layer consisted of Sr, Ba and Ti, however, did not contain Y and Cu. Crystallites of the layer were carefully tilted in the microscope and diffraction patterns were obtained in five different poles for every crystallite. These patterns were consistent with the phase (Ba1-XSrx)2TiO4. The intermediate layer was most likely formed during the annealing at 900°C. Its formation can be understood as a diffusion of Ba from the amorphously deposited film into the substrate and diffusion of Sr from the substrate into the film. Between the intermediate layer and the surface of the film the film consisted of YBa2Cu3O7-x grains. Films prepared in process 1 had Tc(R=0) close to 90 K, however, critical currents were as low as jc = 104A/cm2 at 77 K.

Solubility Enhancement of Poorly Soluble Drug Simvastatin by Solid Dispersion Technique

2016 ◽  
Vol 2 (2) ◽  
pp. 91-95
Author(s):  
Neelima Rani T ◽  
Pavani A ◽  
Sobhita Rani P ◽  
Srilakshmi N
Keyword(s):  
Dissolution Rate ◽  
Drug Carrier ◽  
Solid Dispersions ◽  
Aqueous Solubility ◽  
Onset Of Action ◽  
Kneading Method ◽  
Wetting Property ◽  
Poorly Soluble ◽  
Dispersion Technique ◽  
Low Solubility

This study aims to formulate solid dispersions (SDs) of Simvastatin (SIM) to improve the aqueous solubility, dissolution rate and to facilitate faster onset of action. Simvastatin is a BCS class II drug having low solubility & therefore low oral bioavailability. In the present study, SDs of simvastatin different drug-carrier ratios were prepared by kneading method. The results showed that simvastatin solubility & dissolution rate enhanced with polymer SSG in the ratio 1:7 due to increase in wetting property or possibly may be due to change in crystallinity of the drug.

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