Search results for "Poly(vinylpyrrolidone)"
showing 7 items of 17 documents
Evaluation of drug-polymer solubility curves through formal statistical analysis: comparison of preparation techniques.
2014
ABSTRACT: In this study, the influence of the preparation technique (ball milling, spray drying, and film casting) of a supersaturated amorphous dispersion on the quality of solubility determinations of indomethacin in polyvinylpyrrolidone was investigated by means of statistical analysis. After annealing of the amorphous dispersions above the crystallization temperature for 2 h, the solubility curve was derived from the glass transition temperature of the demixed material using the Gordon–Taylor relationship and fitting with the Flory–Huggins model. The study showed that the predicted solubility from the ball-milled mixtures was not consistent with those from spray drying and film casting,…
Mild Homogeneous Synthesis of Gold Nanoparticles through the Epoxide Route: Kinetics, Mechanisms, and Related One‐Pot Composites
2019
A new one-pot homogeneous methodology at room temperature to obtain Au nanoparticles (AuNP) on the basis of the epoxide route is presented. The proposed method takes advantage of the homogenous generation of OH- moieties driven by epoxide ring-opening, mediated by chloride nucleophilic attack. Once reached alkaline conditions, the reducing medium allows the quantitative formation of AuNP under well-defined kinetic control. A stabilizing agent, such as polyvinylpyrrolidone (PVP) or cetyltrimethylammonium chloride (CTAC), is required to maintain the AuNP stable. Meanwhile their presence dramatically affects the reduction kinetics and pathway, as demonstrated by the evolution of the UV/Vis spe…
Influence of PVP/VA copolymer composition on drug–polymer solubility
2015
In this study, the influence of copolymer composition on drug-polymer solubility was investigated. The solubility of the model drug celecoxib (CCX) in various polyvinylpyrrolidone/vinyl acetate (PVP/VA) copolymer compositions (70/30, 60/40, 50/50 and 30/70 w/w) and the pure homopolymers polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA) was predicted at 25 °C using a thermal analysis method based on the recrystallization of a supersaturated amorphous dispersion (recrystallization method). These solubilities were compared with a prediction based on the solubility of CCX in the liquid monomeric precursors of PVP/VA, N-vinylpyrrolidone (NVP) and vinyl acetate (VA), using the Flory-Huggins …
Consistency of Carbopol 971-P NF gels and influence of soluble and cross-linked PVP.
2002
A study is made of the polymerization process of polyacrylic acid, commercially known as Carbopol® 971 NF, assessing its consistency as a function of the degree of neutralization at pH values from 3 to 12, approximately. Percentage concentrations ranging from 0.1 to 1.4% (w/w) were studied. The gels obtained were non-Newtonian, and pseudoplastic. As concentration and pH rise, the consistency of the gels increase to a maximum, which appears between pH 6 and 8, allowing their use as vehicles in bioadhesive formulations for mucosal application. Over the increasing viscosity interval, functions were obtained to indicate the consistency of the gel as a function of pH and concentration. Since the…
Comparative Study of Different Methods for the Prediction of Drug–Polymer Solubility
2015
In this study, a comparison of different methods to predict drug-polymer solubility was carried out on binary systems consisting of five model drugs (paracetamol, chloramphenicol, celecoxib, indomethacin, and felodipine) and polyvinylpyrrolidone/vinyl acetate copolymers (PVP/VA) of different monomer weight ratios. The drug-polymer solubility at 25 °C was predicted using the Flory-Huggins model, from data obtained at elevated temperature using thermal analysis methods based on the recrystallization of a supersaturated amorphous solid dispersion and two variations of the melting point depression method. These predictions were compared with the solubility in the low molecular weight liquid ana…
Influence of Polymer Molecular Weight on Drug–polymer Solubility: A Comparison between Experimentally Determined Solubility in PVP and Prediction Der…
2015
ABSTRACT: In this study, the influence of polymer molecular weight on drug–polymer solubility was investigated using binary systems containing indomethacin (IMC) and polyvinylpyrrolidone (PVP) of different molecular weights. The experimental solubility in PVP, measured using a differential scanning calorimetry annealing method, was compared with the solubility calculated from the solubility of the drug in the liquid analogue N-vinylpyrrolidone (NVP). The experimental solubility of IMC in the low-molecular-weight PVP K12 was not significantly different from that in the higher molecular weight PVPs (K25, K30, and K90). The calculated solubilities derived from the solubility in NVP (0.31–0.32 …
Supercritical Assisted Atomization: Polyvinylpyrrolidone as Carrier for Drugs with Poor Solubility in Water
2013
Supercritical assisted atomization (SAA) is an efficient technique to produce microparticles and composite microspheres formed by polymers and pharmaceutical compounds. In this work polyvinylpyrrolidone (PVP) was proposed as carrier for pharmaceutical compounds that show a poor solubility in water medium. Indeed, this polymer is hydrosoluble and can be generally used to enhance the dissolution rate of hydrophobic compounds when finely dispersed in it. However, it is difficult to obtain coprecipitates with a uniform dispersion of the active molecule using other micronization techniques. The experiments were performed using ethanol as solvent; SAA plant was operated at 40°C and 76 bar in the …