Preparation of budesonide- and indomethacin-hydroxypropyl-beta-cyclodextrin (HPBCD) complexes using a single-step, organic-solvent-free supercritical fluid process

Budesonide nanoparticle agglomerates as dry powder aerosols with rapid dissolution

Nanoparticle technology represents an attractive approach for formulating poorly water-soluble pulmonary medicines. Unfortunately, nanoparticle suspensions used in nebulizers or metered dose inhalers often suffer from physical instability in the form of uncontrolled agglomeration or Ostwald ripening. In addition, processing such suspensions into dry powders can yield broad particle size distributions. To address these encumbrances, a controlled nanoparticle flocculation process has been developed. Nanosuspensions of the poorly water-soluble drug budesonide were prepared by dissolving the drug in organic solvent containing surfactants followed by rapid solvent extraction in water. Different surfactants were employed to control the size and surface charge of the precipitated nanoparticles. Nanosuspensions were flocculated using leucine and lyophilized. Selected budesonide nanoparticle suspensions exhibited an average particle size ranging from approximately 160 to 230 nm, high yield and high drug content. Flocculated nanosuspensions produced micron-sized agglomerates. Freeze-drying the nanoparticle agglomerates yielded dry powders with desirable aerodynamic properties for inhalation therapy. In addition, the dissolution rates of dried nanoparticle agglomerate formulations were significantly faster than that of stock budesonide. The results of this study suggest that nanoparticle agglomerates possess the microstructure desired for lung deposition and the nanostructure to facilitate rapid dissolution of poorly water-soluble drugs.

Improvement of solubility and dissolution rate of indomethacin by solid dispersions in Gelucire 50/13 and PEG4000

The aim of this study was to prepare and characterize solid dispersions of water insoluble non-steroidal anti-inflammatory drug, indomethacin (IND), with polyethylene glycol 4000 (PEG4000) and Gelucire 50/13 (Gelu.) for enhancing the dissolution rate of the drug. The solid dispersions (SDs) were prepared by hot melting method at 1:1, 1:2 and 1:4 drug to polymer ratios. Scanning electron microscopy (SEM), X-ray powder diffractometry (XRD) and differential scanning calorimetry (DSC) were used to examine the physical state of the drug. Furthermore, the solubility and the dissolution rate of the drug in its different systems were explored. The data from the XRD showed that the drug was still detectable in its solid state in all SDs of IND-Gelu. and disappeared in case of higher ratio of IND-PEG4000. DSC thermograms showed the significant change in melting peak of the IND when prepared as SDs suggesting the change in crystallinity of IND. The highest ratio of the polymer (1:4) enhanced the drug solubility about 4-folds or 3.5-folds in case of SDs of IND-PEG or IND-Gelu., respectively. An increased dissolution rate of IND at pH 1.2 and 7.4 was observed when the drug was dispersed in these carriers in form of physical mixtures (PMs) or SDs. IND released faster from the SDs than from the pure crystalline drug or the PMs. The dissolution rate of IND from its PMs or SDs increased with an increasing amount of polymer.

High-pressure NMR characterization of triacetyl-beta-cyclodextrin in supercritical carbon dioxide

Cyclodextrins are used in many drug formulations since their cavities provide microenvironments where drug molecules can enter and form inclusion complexes for controlled drug delivery. Supercritical carbon dioxide (scCO(2)) is an alternative to organic solvents and a very attractive medium for the preparation of these inclusion complexes. The potential ability of triacetyl-beta-cyclodextrin (TA-beta-CD) to form inclusion complexes in addition to its high miscibility in liquid and scCO(2) could offer a chance for an economical and environmental friendly chemical processing. In this work, high-pressure NMR studies were performed in order to obtain information on the molecular structure and dynamics of TA-beta-CD in scCO(2) at 313.15 K and 20 MPa and its ability to form inclusion complexes under these conditions was studied. The influence of scCO(2) on a number of NMR spectral parameters, such as chemical shifts, spin-spin coupling constants, nuclear Overhauser effect (NOE) and spin-lattice relaxation (T(1)) has been studied. We unequivocally show for the first time structural changes of TA-beta-CD in scCO(2), like acetyl chain orientation and overall shape distortions that can affect its inclusion capability in this medium. The possibility of cavity self-closure is discussed and the results of two inclusion studies that support cavity self-closure, with the angiotensin-converting enzyme inhibitor, captopril, and the nonsteroid anti-inflammatory drug, flufenamic acid, are presented.

Complexation study of the anticancer agent EO-9 with 2-hydroxypropyl-beta-cyclodextrin

For the development of a bladder instillation of the indoloquinone agent EO-9, use of the complexing agent 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) was considered. Therefore, a complexation study of EO-9 with HPbetaCD was performed. Complexation was studied in aqueous solution and in solid freeze-dried products. A phase solubility study, UV-visible spectroscopy (UV/VIS), and analysis of the effect of HPbetaD on the stability of EO-9 were performed. With the phase solubility study, a complexation constant (K1:1) of 32.9, a complexation efficiency (CE) of 0.0457, and a utility number (UCD) of 38.3 were calculated. These K1:1 and CE values indicate a weak complex, but the UCD shows that HPbetaCD can be very useful as solubilizer in the desired formulation. Furthermore, a positive effect of HPbetaCD on the chemical stability of EO-9 in solution was seen. Subsequently, complexation in the freeze-dried products was studied more thoroughly using Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. HPbetaCD was found to be an excellent pharmaceutical complexing agent for application in formulations for EO-9 bladder instillations. Reconstitution before use of the developed freeze-dried products can be simply accomplished with water for injection.

Physicochemical properties of antifungal drug-cyclodextrin complexes prepared by supercritical carbon dioxide and by conventional techniques

Antifungal drugs are the most common systemic drugs used for the treatment of oropharyngeal candidiasis, which is the first symptom of HIV infection. However, the efficacy and bioavailability of these drugs have been limited by their poor aqueous solubility and dissolution rate. Therefore, the aim of this study was to investigate the effect of different preparation methods (i.e. kneading, coevaporation, sealed-heating, and a solid inclusion technique using supercritical carbon dioxide carrier (SC CO(2)-inclusion)) for obtaining solid inclusion complexes between beta-cyclodextrin and three antifungal drugs (itraconazole, econazole, and fluconazole). The physicochemical properties of the different products were characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (PXRD). For the complexes prepared by the SC CO(2)-inclusion method, the effects of temperature and pressure have also been investigated. Results suggested the possibility of complex formation between beta-cyclodextrin and the three antifungal agents, and indicated that inclusion formation was influenced by the preparation technique. SC CO(2)-inclusion method proved to be an effective technique for preparing solid-state inclusion complexes between beta-cyclodextrin and antifungal drugs, avoiding the use of organic solvents. Moreover, temperature of the SC CO(2) played a major role in promoting drug-carrier interactions, whereas pressure had limited effects.

Characterization and drug release investigation of amorphous drug-hydroxypropyl methylcellulose composites made via supercritical carbon dioxide assisted impregnation

Hydroxypropylmethyl cellulose (HPMC)-indomethacin (4:1, w/w) drug composites (DCs) were prepared via supercritical carbon dioxide (sc-CO(2)) assisted impregnation. The effect of processing temperature (at fixed pressures) on the physical and other properties of the resulting HPMC-indomethacin DCs was investigated using a range of analytical techniques, including differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and powder X-ray diffraction (XRD) methods. The data suggest that for a 4:1 (w/w) HPMC-indomethacin ratio prepared at 130 degrees C (17.2 MPa), the indomethacin exists entirely in an amorphous dispersion within the polymer matrix. The primary interaction between HPMC and indomethacin appears to be hydrogen bonding between the carboxylic acid carbonyl group of indomethacin and hydroxyl group of HPMC. The initial (first 15 min) and overall drug release behavior within a 5h timeframe for the HPMC-indomethacin DCs, was analyzed. For the HPMC-indomethacin drug composite processed at 130 degrees C/17.2 MPa, drug release behavior obeyed a n-power law (n=0.54).

Biodegradable particle formation for drug and gene delivery using supercritical fluid and dense gas

Recent developments in biodegradable particle formation using supercritical fluids and dense gases have been reviewed with an emphasis on studies of micronizing and encapsulating poorly-soluble pharmaceuticals and gene. General review articles published in previous years have then been provided. A brief description of the operating principles of some types of particle formation processes is given. These include the rapid expansion of supercritical solutions (RESS), the particles from gas-saturated solution (PGSS) processes, the gas antisolvent process (GAS), and the supercritical antisolvent process (SAS). The papers have been reviewed under two groups, one involving the production of particles from pure biodegradable substances, and the other involving coating, capsule, and impregnation that contain active components, especially those that relate to pharmaceuticals. This review is a comprehensive review specifically focused on the formation of biodegradable particles for drug and gene delivery system using supercritical fluid and dense gas.

Particle design of poorly water-soluble drug substances using supercritical fluid technologies

In order to improve the dissolution properties of poorly water-soluble drugs, some drugs were subjected to micronization or prepared as composite particles using supercritical fluid (SCF) technology with carbon dioxide (CO(2)). Solubility in CO(2) is the key when using this method. Solubility affects the supersaturation of the materials in the solvent as well as the mass transfer of that solvent, which are both critical to the micronization of the materials and the formation of the composite particles. Some useful techniques that can be used to avoid the problems posed by the characteristics of the drug itself are combining SC-CO(2) with other technologies, such as the formation of coacervates or emulsions, and other equipment types, such as milling or ultrasound fields. Another advantage of SCF technology is that it is considered to be green chemistry. SC-CO(2) can improve the solubility of poorly water-soluble drug substances using few or no organic solvents and with little or no heating.

Enhancement of dissolution amount and in vivo bioavailability of itraconazole by complexation with β-cyclodextrin using supercritical carbon dioxide

The main objective of this study was to improve the inclusion formation between itraconazole and beta-cyclodextrin and thus enhance dissolution amount and bioavailability characteristics of itraconazole. Inclusion complexes between itraconazole and beta-cyclodextrin were prepared using simple physical mixing, conventional coprecipitation method, and supercritical carbon dioxide (SC CO(2)). Effects of process variables (temperature, pressure) and drug:cyclodextrin ratio on inclusion yield and thermal behavior of the solid complexes prepared by SC CO(2) were studied and compared to those obtained by physical mixing and coprecipitation methods. In addition, dissolution amounts of the products obtained by different methods were measured in gastric fluid. Finally, pharmacokinetic studies of the inclusion complexes were conducted in male Wistar rats to assess the bioavailability of the prepared complexes. Results showed that temperature, pressure and itraconazole:beta-cyclodextrin ratio had significant effects on the inclusion yield of the complex prepared by SC CO(2) method. Higher inclusion yields were obtained in the SC CO(2) method as compared to physical mixing and coprecipitation methods. In vivo drug pharmacokinetic studies showed that the itraconazole-beta-cyclodextrin product prepared using SC CO(2) gave higher bioavailability of itraconazole (in blood, liver and kidney of male Wistar rats) as compared to the products obtained by physical mixing or coprecipitation methods.

Indomethacin-saccharin cocrystal: design, synthesis and preliminary pharmaceutical characterization

PURPOSE

To design and prepare cocrystals of indomethacin using crystal engineering approaches, with the ultimate objective of improving the physical properties of indomethacin, especially solubility and dissolution rate.

MATERIALS AND METHODS

Various cocrystal formers, including saccharin, were used in endeavours to obtain indomethacin cocrystals by slow evaporation from a series of solvents. The melting point of crystalline phases was determined. The potential cocrystalline phase was characterized by DSC, IR, Raman and PXRD techniques. The indomethacin-saccharin cocrystal (hereafter IND-SAC cocrystal) structure was determined from single crystal X-ray diffraction data. Pharmaceutically relevant properties such as the dissolution rate and dynamic vapour sorption (DVS) of the IND-SAC cocrystal were evaluated. Solid state and liquid-assisted (solvent-drop) cogrinding methods were also applied to indomethacin and saccharin.

RESULTS

The IND-SAC cocrystals were obtained from ethyl acetate. Physical characterization showed that the IND-SAC cocrystal is unique vis-à-vis thermal, spectroscopic and X-ray diffraction properties. The cocrystals were obtained in a 1:1 ratio with a carboxylic acid and imide dimer synthons. The dissolution rate of IND-SAC cocrystal system was considerably faster than that of the stable indomethacin gamma-form. DVS studies indicated that the cocrystals gained less than 0.05% in weight at 98%RH. IND-SAC cocrystal was also obtained by solid state and liquid-assisted cogrinding methods.

CONCLUSIONS

The IND-SAC cocrystal was formed with a unique and interesting carboxylic acid and imide dimer synthons interconnected by weak N-Hcdots, three dots, centeredO hydrogen bonds. The cocrystals were non-hygroscopic and were associated with a significantly faster dissolution rate than indomethacin (gamma-form).

Transformation of pharmaceutical compounds upon milling and comilling: the role of T(g)

Milling is a usual process used in the course of drug formulation, which however may change the physical nature of the end product. The diversity of the transformations of organic compounds upon milling has been widely demonstrated in the pharmaceutical literature. However, no effort has still been devoted to study the correlation between the nature of the transformation and the milling conditions. Results clarifying such transformations are shortly reviewed with special attention paid to the temperature of milling. The importance of the position of the glass transition temperature compared with that of milling is demonstrated. It is shown that decreasing the milling temperature leads to an increase of the amorphization tendency whereas milling above T(g) can produce a crystal-to-crystal transformation between polymorphic varieties. These observations contradict the usual suggestion that milling transforms the physical state only by a heating effect which induces a local melting. Equilibrium thermodynamics does not seem appropriate for describing the process. The driven alloys concept offers a more rational framework to interpret the effect of the milling temperature. Other results are also presented, which demonstrate the possibility for milling to form low temperature solid-state alloys that offer new promising ways to stabilize amorphous molecular solids.

Preparation and characterization of simvastatin/hydroxypropyl-β-cyclodextrin inclusion complex using supercritical antisolvent (SAS) process

In the present study, the practically insoluble drug, simvastatin (SV), and its inclusion complex with hydroxypropyl beta-cyclodextrin (HP-beta-CD) prepared using supercritical antisolvent (SAS) process were investigated to improve the aqueous solubility and the dissolution rate of drug, thus enhancing its bioavailability. Inclusion complexation in aqueous solution and solid state was evaluated by the phase solubility diagram, differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The phase solubility diagram with HP-beta-CD was classified as A(L)-type at all temperatures investigated, indicating the formation of 1:1 stoichiometric inclusion complex. The apparent complexation constants (K(1:1)) calculated from phase solubility diagram were 774, 846 and 924 M(-1) at 25, 37 and 45+/-0.5 degrees C, respectively. No endothermic and characteristic diffraction peaks corresponding to SV was observed for the inclusion complex in DSC and PXRD. FT-IR study demonstrated the presence of intermolecular hydrogen bonds between SV and HP-beta-CD in inclusion complex, resulting in the formation of amorphous form. Aqueous solubility and dissolution studies indicated that the dissolution rates were remarkably increased in inclusion complex, compared with the physical mixture and drug alone. Moreover, SV/HP-beta-CD inclusion complex performed better than SV in reducing total cholesterol and triglyceride levels. This could be primarily attributed to the improved solubility and dissolution associated with inclusion complex between drug and HP-beta-CD. In conclusion, SAS process could be a useful method for the preparation of the inclusion complex of drug with HP-beta-CD and its solubility, dissolution rate and hypolipidemic activity were significantly increased by complexation between SV and HP-beta-CD.

Crystal structure changes of gamma-cyclodextrin after the SEDS process in supercritical carbon dioxide affect the dissolution rate of complexed budesonide

PURPOSE

The present study describes the crystal structure changes of gamma-cyclodextrin (gamma-CD) during the solution enhanced dispersion by supercritical fluids (SEDS) process and its effect on dissolution behaviour of complexed budesonide.

MATERIALS AND METHODS

gamma-CD solution (10 mg/ml in 50% ethanol) was pumped together with supercritical carbon dioxide through a coaxial nozzle with or without a model drug, budesonide (3.3 mg/ml). The processing conditions were 100 b and 40, 60 or 80 degrees C. gamma-CD powders were characterised before and after vacuum-drying (2-3 days at RT) with XRPD, SEM and NMR. Budesonide/gamma-CD complexation was confirmed with DSC and XRPD. The dissolution behaviour of complexed budesonide was determined in aqueous solution (1% gamma-CD, 37 degrees C, 100 rpm).

RESULTS

During the SEDS process (100 b, 40 and 60 degrees C), gamma-CD and budesonide/gamma-CD complexes crystallized in a tetragonal channel-type form. The vacuum-drying transformed crystalline gamma-CD into amorphous form while the complexes underwent a tetragonal-to-hexagonal phase transition. The increase in the processing temperature decreased the crystallinity of gamma-CD. At 80 degrees C, amorphous gamma-CD was obtained while the complexes crystallized in a hexagonal channel-type form. The dissolution behaviour of budesonide/gamma-CD complexes was dependent on their crystal structure: the tetragonal form dissolved faster than the hexagonal form.

CONCLUSIONS

The crystal structure of gamma-CD and subsequently, the dissolution rate of complexed budesonide, can be modified with the processing conditions.

Comparative Evaluation of Ibuprofen/β-Cyclodextrin Complexes Obtained by Supercritical Carbon Dioxide and Other Conventional Methods

PURPOSE

The preparation of drug/cyclodextrin complexes is a suitable method to improve the dissolution of poor soluble drugs. The efficacy of the Controlled Particle Deposition (CPD) as a new developed method to prepare these complexes in a single stage process using supercritical carbon dioxide is therefore compared with other conventional methods.

MATERIALS AND METHODS

Ibuprofen/beta-cyclodextrin complexes were prepared with different techniques and characterized using FTIR-ATR spectroscopy, powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). In addition, the influences of the processing technique on the drug content (HPLC) and the dissolution behavior were studied.

RESULTS

Employing the CPD-process resulted in a drug content of 2.8+/-0.22 wt.% in the carrier. The material obtained by CPD showed an improved dissolution rate of ibuprofen at pH 5 compared with the pure drug and its physical mixture with beta-cyclodextrin. In addition CPD material displays the highest dissolution (93.5+/- 2.89% after 75 min) compared to material obtained by co-precipitation (61.3 +/-0.52%) or freeze-drying (90.6 +/-2.54%).

CONCLUSION

This study presents the CPD-technique as a well suitable method to prepare a drug/beta-cyclodextrin complex with improved drug dissolution compared to the pure drug and materials obtained by other methods.

Applications pharmaceutiques du dioxyde de carbone supercritique

The supercritical state of a fluid is intermediate between that of gases and liquids. Supercritical fluids exhibit some solvent power which is tunable in function of pressure and temperature. In the pharmaceutical field, supercritical carbon dioxide is by far the most commonly used fluid; of course, the first applications of supercritical fluids were the replacement of organic solvents in extraction processes; other applications appeared during the last twenty years: supercritical fluids are also used as eluents in chromatography, as solvents in organic synthesis or for the processing of solid dosage forms by drug micronization, by the production of nanospheres, of solid dispersions, of porous polymeric matrices containing different active substances. Supercritical carbon dioxide has been proposed for encapsulating both hydrophilic and hydrophobic drug substances into liposomes as well as for including different active substances into cyclodextrins. There are also future prospects for the use of pressurized carbon dioxide as a sterilizing agent.

Preparation of budesonide/γ‐cyclodextrin complexes in supercritical fluids with a novel SEDS method

The aim was to investigate if solid drug/cyclodextrin complexes could be produced in a single-step process with a solution enhanced dispersion by supercritical fluids (SEDS) method. Budesonide and gamma-cyclodextrin (CD) solutions (50% or 99.5% ethanol) were pumped from the same (conventional method) or separate (modified method) containers together with supercritical carbon dioxide through a coaxial nozzle into a particle formation chamber. The pressure was maintained at 100, 150 or 200 bar with a temperature of 40, 60 or 80 degrees C. SEDS-processed powders were characterised with HPLC, DSC and XRPD for budesonide content, complexation and crystallinity. The budesonide dissolution rate was determined in 1% gamma-CD aqueous solution. Solid, white budesonide/gamma-CD complex particles were formed using the conventional and modified SEDS processes. The complexation efficiency was dependent on the processing conditions. For example, with the conventional method (100 bar, 60 degrees C) the yield of the powder was 65+/-12% with 0.14+/-0.02 mg budesonide/mg powder, corresponding to 1:2 drug:CD molar ratio. The dissolution rate of this complexed budesonide (93+/-2% after 15 min) was markedly higher compared to unprocessed micronised budesonide (41+/-10%) and SEDS-processed budesonide without CD (61+/-3%). As a conclusion, SEDS is a novel method to produce solid drug/CD complexes in a single-step process.

Preparation of hydrophobic drugs cyclodextrin complex by lyophilization monophase solution

A novel method was evaluated for preparation of hydrophobic drugs cyclodextrin (CD) complex in this study. To obtain sterilized drug-CD complex lyophilized powder for injection or other purpose, the CD solution in water and the hydrophobic drug in tertiary butyl alcohol (TBA) were mixed in a suitable volume ratio, filtered through 0.22 microm millpores, and subsequently freeze-dried. A high drug concentration was obtained in the co-solvent due to the good solvency of TBA, which is miscible with water in any proportion, for hydrophobic drugs. Moreover, TBA could be removed rapidly and completely by freeze-drying because of its high vapor pressure and high melting point. The chemical stability of some labile active compounds was also improved in TBA-water co-solvent. Based on the data from differential scanning calormetry (DSC) and X-ray diffractometry (XRD), drug was amorphous in freeze-dried complex. The fourier transform infrared spectra indicated drug-CD interaction was present in drug-CD complex. An enhanced dissolution rate was also obtained in drug-CD complex. These results proved drug-CD complex had been formed after this technique. Thus, this report provided a simple, efficient, and economic technique for preparation of hydrophobic drugs CD complex, which may be useful practically in modifying hydrophobic drugs physicochemical properties and improving their absorption and pharmacodynamics.

A general ultrasound-assisted access to room-temperature ionic liquids

The replacement of common organic solvents by room-temperature ionic liquids (RTILs) is a topical subject in both academia and industry. In the last decades, the number of applications for RTILs has followed an exponential curve and spilled over the boundaries of chemistry. Still, one of the main drawbacks of these compounds is their difficult access. The present ultrasound-assisted method affords a general and easy access to a large variety of room-temperature ionic liquids.