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► Solubility of pharmaceutical compounds in carbon dioxide are shown to be correlated with a solvation equation that allows also the prediction. ► Ranges of temperature and pressure ...covered are between 308–358K and 100–500bar. ► The accuracy is close to that obtained with other thermodynamic methods.
The solubility of pharmaceutical solid compounds in supercritical carbon dioxide is of great importance in a wide range of applications that include: development of drug delivery systems, powder processing, and precipitation/crystallization processes.
This manuscript aims to estimate the solubility behavior of pharmaceutical compounds in supercritical fluids using an activity coefficient model based on linear solvation energy relationships. The parameters of this model were further generalized as a function of the properties of the pharmaceutical compounds. The selected compounds include antioxidants, antibiotics, steroids and anti-inflammatory and their solubility data were collected from literature.
This model is able to estimate the solubility of the pharmaceutical compounds in supercritical carbon dioxide within acceptable accuracy for more than 60% of the proposed systems.
The role of the interactions in systems containing polymers for the definition of operative conditions in the supercritical fluid processing is reviewed. The approaches used for the study of the ...behaviour of polymers in presence of supercritical fluids are considered also in the case of mixtures containing more than two components. The attention is focused mainly on the thermodynamic properties of the systems.
The purpose of this study was to apply the attractive technique of the supercritical fluid to the preparation of solvent-free solid dispersions. In particular, the gas antisolvent crystallisation ...technique (GAS), using supercritical carbon dioxide as processing medium, has been considered to prepare an enhanced release dosage form for of the poorly soluble carbamazepine, employing PEG 4000 as a hydrophilic carrier. The physical characterisation of the systems using laser granulometer, powder X-ray diffraction, thermal analyses, and scanning electron microscopy was carried out in order to understand the influence of this technological process on the physical status of the drug. The results of the physical characterisation attested a substantial correspondence of the solid state of the drug before and after treatment with GAS technique, whereas a pronounced change in size and morphology of the drug crystals was noticed. The dramatic reduction of the dimensions and the better crystal shape, together with the presence of the hydrophilic polymer determined a remarkable enhancement of the in vitro drug dissolution rate.
The most important effect of sorption of compressed gases and supercritical fluids into glassy polymers is the reduction of the glass transition temperature (T g). This plasticization effect causes ...changes in mechanical and thermophysical properties of the polymers. In this work, a thermodynamic study based on experimental and theoretical results is addressed. New data were carried out for poly(2,6-dimethylphenylene oxide) (PPO), poly(acrylic acid) (PAA), and the copolymer vinylpyrrolidone−vinyl acetate P(VP−VA) using an inverse gas chromatographic technique. To model the T g behavior of diluent−polymer systems, a model that couples the lattice-fluid equation of state and the Gibbs−DiMarzio criterion was used. A parametric study of the influence of the physical properties (lattice coordination number, molecular weight, and binary interaction parameter) on the T g behavior is presented. The thermodynamic model fairly describes the experimental data measured in this work and gives a phenomenological representation of the retrograde vitrification for the systems PPO−CO2, PVP−CO2, and P(VP−VA)−CO2.
A supercritical antisolvent precipitation process was applied to recrystallize vitamin B6 from ethanol solution in CO2. By means of the Peng–Robinson equation of state (PR EoS), we performed ...preliminary studies to identify better operative conditions in terms of the organic solvent, pressure, temperature, and ability to carry a precipitate of the solute. This simulation was also considered to estimate the vitamin B6 particle size starting from supersaturation conditions.
Infinite-dilution activity coefficients for nine classes of volatile organic compounds (paraffins, olefins, cycloparaffins, aromatics, ketones, nitriles, alcohols, esters, and chlorocompounds) in a ...series of four cyclic olefin copolymers were determined using an inverse gas chromatography technique with a packed column. Abraham’s equation of solvation was used for the evaluation of the different types of interactions between the solvents and polymers. The results are compared with the activity coefficients at infinite dilution obtained for other polymers of similar use.
Supercritical impregnation of polymers Kikic, Ireneo; Vecchione, Febe
Current opinion in solid state & materials science,
08/2003, Letnik:
7, Številka:
4
Journal Article
Recenzirano
The interest in the supercritical fluid impregnation of polymeric materials stems from the opportunity to utilize high diffusivity, low surface tension and the ease of solvent recovery for the ...preparation of new polymeric materials. This term includes a wide range of applications of the supercritical impregnation process that will be discussed in this review: preparation of drug delivery systems via impregnation of an active principle in a polymer matrix, dye and organic metallic complexes impregnation and polymer blends preparation via impregnation of a monomer and an initiator in a swollen polymer matrix.
Flavonoids have attracted a lot of attention due to their antioxidant, antitumor and antibacterial activities. Quercetin (3,5,7,3,4-pentahydroxyflavone) is a polyphenolic flavonoid that shows several ...biological effects including a strong inhibitory effect on the growth of several human and animal cancer cell lines and enhances the antiproliferative effect of cisplatin both in-vitro and in-vivo. In spite of a variety of its biological effects, Quercetin is very poorly soluble in water, which has limited its absorption upon oral administration. As known, the solubility of drug is often due to the increase of the surface/volume ratio which implies the increase of the number of surface atoms (or molecules) with respect to the number of bulk atoms (or molecules). With this aim, we investigated the use of supercritical antisolvent (SAS) technique for Quercetin microparticles generation finding the best operative conditions through the Peng Robinson's Equation of State. The obtained simulation behaviors were confirmed by experimental precipitation: the physicochemical characterizations of the samples were also performed. Key words: Quercetin, supercritical antisolvent technique, micronisation, physicochemical characterization
The purpose of this study was to apply the supercritical CO
2 impregnation process for preparing solvent-free nimesulide (NMS)–betacyclodextrins (BCD) association systems with enhanced drug ...dissolution rate. Several drug-to-carrier molar ratios were tested (1:1; 1:2.5; 1:3.5) at different conditions of temperatures (40, 100, and 130 °C) and pressures (140, 190 or 220 bar). The physical and morphological characterisation of the systems using powder X-ray diffraction, thermal analysis, diffuse reflectance Fourier transform-infrared spectroscopy and scanning electron microscopy was carried out to understand the influence of this technological process on the physical status of single components and binary systems and to detect possible interactions between drug and carrier. These analyses provided no evidence of a complete inclusion of NMS in the carrier but the existence of interactions between drug and carrier together with a partial dehydration of the BCD and the formation of drug crystallites with lower melting point and heat of fusion than the native NMS. These phenomena were more intense when severe conditions of pressure and temperature (220 bar and 130 °C) were used during impregnation trials and when the amount of BCD augmented in the systems. These activated solid state of the impregnated systems promoted an enhancement of drug dissolution rate that, in keeping with the results of the physical characterisation, was function of the process conditions and BCD content.
