New Perspectives for Fixed Dose Combinations of Poorly Water-Soluble Compounds: a Case Study with Ezetimibe and Lovastatin.

PURPOSE: Aiming to improve the dissolution rate of ezetimibe (EZE) and lovastatin (LOV) in a fixed dose combination (FDC), co-amorphous systems and ternary solid dispersions were prepared by quench cooling and spray drying, respectively. METHODS: Formulations were characterized through X-ray diffraction, modulated differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy and laser diffraction, and evaluated by 'in vitro' dissolution. Stability studies were conducted at different conditions during 30 days with the ternary solid dispersion composed of 75% of Soluplus® (ELS 1:1 75%). RESULTS: Single phase co-amorphous systems made up of the pure drugs were not able to increase the dissolution rate of EZE and LOV. However, ternary solid dispersions achieved high dissolution for both compounds, especially when Soluplus® was used as carrier. The dissolution efficiency increased up to 18 (EZE) and 6 (LOV) times in ternary solid dispersions, compared to the crystalline drugs. ELS 1:1 75% preserved its amorphous state during 30 days, in different stability conditions. CONCLUSIONS: A spray dried ternary solid dispersion able to enhance the dissolution rate of two poorly soluble, therapeutically complementary drugs, is reported for the first time. These promising results open new perspectives for the development of more advanced FDCs.

Agglomeration of mesoporous silica by melt and steam granulation. part II: screening of steam granulation process variables using a factorial design.

The objectives of this study were to identify the key process parameters during steam granulation of disordered mesoporous silica material Syloid® 244 FP (244) and to compare two different binders: polyvinylpyrrolidone (PVP) K25 and hydroxypropylmethyl cellulose (HPMC). Itraconazole (ITZ) was selected as the model compound for the development of an oral dosage form for enhanced release. Six factors: binder content, steam amount, mixing time, impeller speed, spray pause time, and filler content were investigated using a two-level quarter-fraction factorial design of experiment (DOE) for each binder type. As experimental responses, characteristics correlating to both granules and tablets were selected. Granules prepared from PVP resulted in an overall higher bulk density, granule size, increased flow properties, and better compression and compaction behavior. Although granulation with PVP resulted in the most ITZ to extract from the pores during processing, the premature drug release was less than 5%. The results of the DOE indicate that the risk of extracting the drug from the pores during processing is governed both by the process parameters and the binder properties. Centerpoint replicates of granules prepared with HPMC were highly variable.

Agglomeration of mesoporous silica by melt and steam granulation. Part I: a comparison between disordered and ordered mesoporous silica.

The objective of this study was to compare agglomerations by melt and steam granulation of ordered, COK-12, and disordered, Syloid(®) 244 FP (244), mesoporous silica material. Poloxamer 188 (P188) and polyvinylpyrrolidone K25 (PVP) were chosen as binders for melt and steam granulation, respectively. The poorly water-soluble compound, itraconazole (ITZ), was selected for the development of an immediate-release oral dosage form. Steam granulation resulted in the largest granules, however, the slowest release. Compression behavior and tablet properties of steam-granulated material prepared with COK-12 and 244 were similar. As determined by X-ray powder diffraction, melt granulation resulted in the most ITZ to extract from the pores during processing. However, the enhanced release rate was still maintained when compared with the crystalline form. Moreover, no additional drug extraction was observed following the 6 month storage in 25°C/60% relative humidity (RH) and 40°C/75%RH. P188 diffraction peaks were present in the 244 melt-granulated material, but disappeared because of the degradation following 1 week in 40°C/75%RH conditions. The differential scanning calorimetry analysis indicated that the degradation of P188 already occurred during the granulation process itself. Based on these results, steam granulation with PVP is the preferred method over melt granulation with P188.

Drug release modification by interpolymer interaction between countercharged types of Eudragit® RL 30D and FS 30D in double-layer films.

Interpolymer interactions between the countercharged methacrylate copolymers Eudragit(®) RL 30D (polycation) and Eudragit(®) FS 30D (polyanion), were investigated in conditions mimicking the gastrointestinal environment. The formation of inter-macromolecular ionic bonds between Eudragit(®) RL 30D and Eudragit(®) FS 30D was investigated using FT-IR spectroscopy and modulated DSC. The FT-IR spectra of the tested polymeric matrices are characterized by visible changes in the observed IR region indicating the interaction between chains of two oppositely charged copolymers. A new band at 1570 cm(-1) appeared which was assigned to the absorption of the carboxylate groups that form the ionic bonds with the quaternary ammonium groups. Moreover, while increasing the pH values from pH 5.8 to 7.4, a decrease of the intensity of the band at 960 cm(-1) (quaternary ammonium group vibration) was observed. All binary mixtures were characterized by the presence of only one and narrow Tg, pointing to sample homogeneity, because of the compatibility of components. As a result of electrostatic interaction between the copolymer chains during swelling, the resulting Tg is decreased significantly and was dependent on the quantity of copolymers present in the structure of polycomplexes formed. Overall, the interaction between countercharged copolymers during passage in gastrointestinal tract can strongly modify the release profile of the model drug diclofenac sodium.

Effect of compression on non-isothermal crystallization behaviour of amorphous indomethacin.

PURPOSE: To evaluate the effect of tablet compression on the physical stability of amorphous indomethacin. METHODS: The amorphous indomethacin generated by melt cooling, rapid (5°C/min) or slow (0.2°C/min) cooling, was evaluated by PXRD, mDSC and FTIR analysis. Non-isothermal crystallisation behaviour was assessed using mDSC and any structural changes with compression were monitored by FTIR. Amorphous indomethacin was compressed in a DSC pan using a custom made die cavity-punch setup and further analysed in the primary container to minimize stress due to sample transfer and preparation. RESULTS: Compression of amorphous indomethacin induced and increased the extent of crystallisation upon heating. DSC results revealed that amorphous indomethacin generated by rapid cooling is more prone to compression induced crystallisation than the slowly cooled one. Onset temperature for crystallisation (T(c)) of uncompressed slowly and rapidly cooled samples are 121.4 and 124°C and after compression T(c) decreased to ca 109 and ca 113°C, respectively. Compression of non-aged samples led to higher extent of crystallisation predominantly into γ-form. Aging followed by compression led to crystallisation of mainly the α-form. CONCLUSIONS: Compression affects the physical stability of amorphous indomethacin. Structural changes originated from tablet compression should be duly investigated for the stable amorphous formulation development.

Influence of preparation methods on solid state supersaturation of amorphous solid dispersions: a case study with itraconazole and eudragit e100.

PURPOSE: The present study aims to determine the drug / polymer miscibility level as a function of the preparation method for an amorphous solid dispersion model system containing itraconazole and eudragit E100. This value was compared to the theoretical crystalline drug solubility in the amorphous polymer and the miscibility of the amorphous drug in the amorphous polymer. METHODS: The amorphous solid dispersions were prepared via spray drying and film casting in order to evaluate the influence of the solvent drying rate. The experimental miscibility level was estimated using XRPD, MDSC, FT-IR, HPLC and TGA. The solubility and miscibility were estimated using the Flory-Huggins mixing theory and experimental drug in monomer solubility data. RESULTS: The experimental miscibility level was found to be 27.5% w/w for spray-dried and 15% for film-casted solid dispersions. FT-IR measurements confirmed the absence of saturable interactions like hydrogen bonds, and analysis of the mixed glass transition temperatures suggested low adhesion forces in the amorphous mixture. The solubility analysis rendered a positive FH interaction parameter, a crystalline solubility of approximately 0.012% w/w and an amorphous drug-polymer miscibility of approximately 7.07% w/w. CONCLUSION: The solid dispersions are significantly supersaturated with respect to both crystalline solubility and amorphous miscibility demonstrating the influence of manufacturing methodology.

Spray drying from complex solvent systems broadens the applicability of Kollicoat IR as a carrier in the formulation of solid dispersions.

The presented study aims to explore the feasibility of preparing solid dispersions of the poorly soluble drug, itraconazole, with Kollicoat IR via spray drying, in order to broaden the application window of the polymer. In order to circumvent the need for a common solvent, Kollicoat IR was dissolved in a 50/50 (v/v) water/ethanol mixture and itraconazole was dissolved in a 50/50 (v/v) dichloromethane/ethanol mixture. In a first approach these two solutions were simultaneously spray dried via a spray nozzle with two inlets. In a second approach the two solutions were mixed prior to spray drying and the metastable solution was spray dried via a spray nozzle with a single inlet. This approach was also varied by adding HCl to the water phase of the Kollicoat IR solution. The resulting solid dispersions were characterized with MDSC, XRPD and their dissolution was followed in SGF. The results of the three data sets show that as the mixing between itraconazole and Kollicoat IR improves, the dissolution improves as well. Using the first approach, no mixing was observed between polymer and drug. The second approach on the other hand led to a reasonable degree of mixing as the solid dispersions were XRPD amorphous and no glassy mesofase of itraconazole was observed.

Influence of polyethylene glycol chain length on compatibility and release characteristics of ternary solid dispersions of itraconazole in polyethylene glycol/hydroxypropylmethylcellulose 2910 E5 blends.

The present study aims to elucidate the influence of the polyethylene glycol chain length on the miscibility of PEG/HPMC 2910 E5 polymer blends, the influence of polymer compatibility on the degree of molecular dispersion of itraconazole, and in vitro dissolution. PEG 2000, 6000, 10,000 and 20,000 were included in the study. Solid dispersions were prepared by spray drying and characterized with MDSC, XRPD and in vitro dissolution testing. The polymer miscibility increased with decreasing chain length due to a decrease in the Gibbs free energy of mixing. Recrystallization of itraconazole occurred as soon as a critical temperature of ca. 75 degrees C was reached for the glass transition that represents the ternary amorphous phase. Due to the lower miscibility degree between the longer PEG types and HPMC 2910 E5, the ternary amorphous phase was further separated, leading to a more rapid decrease of the ternary amorphous phase glass transition as a function of PEG and itraconazole weight percentage and hence, itraconazole recrystallization. In terms of release, an advantage of the shorter chain length PEG types (2000, 6000) over the longer chain length PEG types (10,000, 20,000) was observed for the polymer blends with 5% of PEG with respect to the binary itraconazole/HPMC 2910 E5 solid dispersion. Among the formulations with a 15/85 (w/w) PEG/HPMC 2910 E5 ratio on the other hand, there was no difference in the release profile.

The effect of pressurized carbon dioxide as a temporary plasticizer and foaming agent on the hot stage extrusion process and extrudate properties of solid dispersions of itraconazole with PVP-VA 64.

The aim of the current research project was to explore the possibilities of combining pressurized carbon dioxide with hot stage extrusion during manufacturing of solid dispersions of itraconazole and polyvinylpyrrolidone-co-vinyl acetate 64 (PVP-VA 64) and to evaluate the ability of the pressurized gas to act as a temporary plasticizer as well as to produce a foamed extrudate. Pressurized carbon dioxide was injected into a Leistritz Micro 18 intermeshing co-rotating twin-screw melt extruder using an ISCO 260D syringe pump. The physicochemical characteristics of the extrudates with and without injection of carbon dioxide were evaluated with reference to the morphology of the solid dispersion and dissolution behaviour and particle properties. Carbon dioxide acted as plasticizer for itraconazole/PVP-VA 64, reducing the processing temperature during the hot stage extrusion process. Amorphous dispersions were obtained and the solid dispersion was not influenced by the carbon dioxide. Release of itraconazole from the solid dispersion could be controlled as a function of processing temperature and pressure. The macroscopic morphology changed to a foam-like structure due to expansion of the carbon dioxide at the extrusion die. This resulted in increased specific surface area, porosity, hygroscopicity and improved milling efficiency.

Comparative evaluation of co-processed lactose and microcrystalline cellulose with their physical mixtures in the formulation of folic acid tablets.

In this study, a new co-processed filler-binder ingredient for direct compression, MicroceLac 100, was compared with three different lactoses mixed with microcrystalline cellulose. The aim was to improve a folic acid tablet formulation. Therefore, the influence of drug addition to these mixtures was studied with regard to flow and binding properties. Another part of the study was focused on the interaction and segregation behavior of the drug. MicroceLac 100 showed superior flow and binding properties. Good adhesion of folic acid to the MicroceLac 100 particles could decrease demixing and segregation. The improved characteristics of co-processed material are attributed to spray drying. Sodium stearyl fumarate was chosen as a lubricant, based on ejection force measurements. The content uniformity of the newly formulated direct compression tablets met the official requirements.