Micronization of drug particles via RESS process

Impact of Leucine and Magnesium Stearate on the Physicochemical Properties and Aerosolization Behavior of Wet Milled Inhalable Ibuprofen Microparticles for Developing Dry Powder Inhaler Formulation

This study investigated the development and characterization of leucine and magnesium stearate (MgSt) embedded wet milled inhalable ibuprofen (IBF) dry powder inhaler (DPI) formulations. IBF microparticles were prepared by a wet milling homogenization process and were characterized by SEM, FTIR, DSC, XRD and TGA. Using a Twin-Stage Impinger (TSI), the in vitro aerosolization of the formulations with and without carrier lactose was studied at a flow rate of 60± 5 L/min and the IBF was determined using a validated HPLC method. The flow properties were determined by the Carr's Index (CI), Hausner Ratio (HR) and Angle of Repose (AR) of the milled IBF with 4-6.25% leucine and leucine containing formulations showed higher flow property than those of formulations without leucine. The fine particle fraction (FPF) of IBF from the prepared formulations was significantly (p = 0.000278) higher (37.1 ± 3.8%) compared to the original drug (FPF 3.7 ± 0.9%) owing to the presence of leucine, which enhanced the aerosolization of the milled IBF particles. Using quantitative phase analysis, the XPRD data revealed the crystallinity and accurate weight percentages of the milled IBF in the formulations. FTIR revealed no changes of the structural integrity of the milled IBF in presence of leucine or MgSt. The presence of 2.5% MgSt in the selected formulations produced the highest solubility (252.8 ± 0.6 µg/mL) of IBF compared to that of unmilled IBF (147.4 ± 1.6 µg/mL). The drug dissolution from all formulations containing 4-6.25% leucine showed 12.2-18.6% drug release in 2.5 min; however, 100% IBF dissolution occurred in 2 h whereas around 50% original and dry milled IBF dissolved in 2 h. The results indicated the successful preparation of inhalable IBF microparticles by the wet milling method and the developed DPI formulations with enhanced aerosolization and solubility due to the presence of leucine may be considered as future IBF formulations for inhalation.

Liposomal formulations for treating lysosomal storage disorders

Lysosomal storage disorders (LSD) are a group of rare life-threatening diseases caused by a lysosomal dysfunction, usually due to the lack of a single enzyme required for the metabolism of macromolecules, which leads to a lysosomal accumulation of specific substrates, resulting in severe disease manifestations and early death. There is currently no definitive cure for LSD, and despite the approval of certain therapies, their effectiveness is limited. Therefore, an appropriate nanocarrier could help improve the efficacy of some of these therapies. Liposomes show excellent properties as drug carriers, because they can entrap active therapeutic compounds offering protection, biocompatibility, and selectivity. Here, we discuss the potential of liposomes for LSD treatment and conduct a detailed analysis of promising liposomal formulations still in the preclinical development stage from various perspectives, including treatment strategy, manufacturing, characterization, and future directions for implementing liposomal formulations for LSD.

Supercritical fluid (SCF)-assisted fabrication of carrier-free drugs: An eco-friendly welcome to active pharmaceutical ingredients (APIs)

Despite the success in developing various pharmaceutical formulations, most of the active pharmaceutical ingredients (APIs)/drugs, according to the Biopharmaceutics Classification System (BCS), often suffer from various intrinsic limitations of solubility and permeability, substantially hindering their bioavailability in vivo. Regardless of the fact that the availability of different particle fabrication approaches (top-down and bottom-up) towards pharmaceutical manufacturing, the supercritical fluid (SCF) technology has emerged as one of the highly effective substitutes due to the environmentally benign nature and processing convenience, as well as the economically promising character of SCFs. The exceptional features of SCFs have endowed the fabrication of various APIs either solely or in combination with the compatible supramolecular species towards achieving improved drug delivery. Operating such APIs in high-pressure conditions often results in arbitrary-sized particulate forms, ranging from micron-sized to sub-micron/nano-sized particles. Comparatively, these SCF-processed particles offer enhanced tailorable physicochemical and morphological properties (size, shape, and surface), as well as improved performance efficacy (bioavailability and therapy) over the unprocessed APIs. Although the "carrier-based" delivery is practical among diverse delivery systems, the direct fabrication of APIs into suitable particulate forms, referred to as "carrier-free" delivery, has increased attention towards improving the bioavailability and conveying a high payload of the APIs. This review gives a comprehensive emphasis on the SCF-assisted fabrication of diverse APIs towards exploring their great potential in drug delivery. Initially, we discuss various challenges of drug delivery and particle fabrication approaches. Further, different supercritical carbon dioxide (SC-CO₂)-based fabrication approaches depending on the character of SCFs are explicitly described, highlighting their advantages and suitability in processing diverse APIs. Then, we provide detailed insights on various processing factors affecting the properties and morphology of SCF-processed APIs and their pharmaceutical applications, emphasizing their performance efficacy when administered through multiple routes of administration. Finally, we summarize this compilation with exciting perspectives based on the lessons learned so far and moving forward in terms of challenges and opportunities in the scale-up and clinical translation of these drugs using this innovative technology.

Use of Spray Flash Evaporation (SFE) technology to improve dissolution of poorly soluble drugs: Case study on furosemide nanocrystals

The poor solubility and related low bioavailability are a major concern for a large number of small molecule drugs, both on the market and in development. Several formulation strategies exist to overcome this issue. Among them, particle engineering is of outmost importance. The aim of this work is to present the potential of Spray Flash Evaporation (SFE), a new technology for drug particle engineering. To assess the potential of SFE, we carried out a case study on the nano-crystallization of furosemide, a BCS class IV drug. A thorough characterization of the obtained nanocrystals is presented along with a study of dissolution which highlights the solubility improvement provided by nanocrystals produced via SFE technology. The obtained results show a particle size reduction when compared to the raw material, as well as an increase of the dissolution rate of 4.5-fold.

Trends on the Rapid Expansion of Supercritical Solutions Process Applied to Food and Non-food Industries

BACKGROUND

The supercritical fluids applied to particle engineering over the last years have received growing interest from the food and non-food industries, in terms of processing, packaging, and preservation of several products. The rapid expansion of supercritical solutions (RESS) process has been recently reported as an efficient technique for the production of free-solvent particles with controlled morphology and size distribution.

OBJECTIVE

In this review, we report technological aspects of the application of the RESS process applied to the food and non-food industry, considering recent data and patent survey registered in literature.

METHODS

The effect of process parameters cosolvent addition, temperature, pressure, nozzle size among others, during RESS on the size, structure and morphology of the resulted particles, and the main differences about recent patented RESS processes are reviewed.

RESULTS

Most of the experimental works intend to optimize their processes through investigation of process parameters.

CONCLUSION

RESS is a feasible alternative for the production of particles with a high yield of bioactive constituents of interest to the food industry. On the other hand, patents developed using this type of process for food products are very scarce, less attention being given to the potential of this technique to develop particles from plant extracts with bioactive substances.

Recrystallization and Micronization of p-Toluenesulfonamide Using the Rapid Expansion of Supercritical Solution (RESS) Process

This study is focused on the micronization of p-toluenesulfonamide (p-TSA) using the rapid expansion of supercritical solution (RESS) process. Taguchi’s experimental design method was applied to determine the optimum operating conditions. L9(34) orthogonal array with four control factors and three levels of each control factor was used to design nine experimental conditions. Four control factors were selected, including extraction temperature, extraction pressure, pre-expansion temperature, and post-expansion temperature. The particle size and morphology of the prepared samples were observed by scanning electron microscopy (SEM). In addition, Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were employed to compare the differences between the raw and micronized p-TSA particles. The experimental and analytical results indicated that the extraction temperature was the most significant factor for the micronization of p-TSA in the RESS process, and the optimal operating conditions were at an extraction temperature of 50 °C, an extraction pressure of 220 MPa, a pre-expansion temperature of 220 °C, and a post-expansion temperature of 30 °C. The p-TSA particles were micronized from the original average size of 294.8 μm to the smallest average size of 1.1 μm at the optimal RESS process conditions. Furthermore, the physicochemical characteristics of p-TSA did not differ significantly before and after recrystallization.

Evaluation of the Potential Use of Laminar Extrudates on Stabilizing Micronized Coumarin Particles by Supercritical Fluids (RESS)-Study of Different RESS Processing Variables and Mode of Operation

The study evaluates the ability of extrudates to deliver coumarin particles micronized by the rapid expansion of supercritical solutions (RESS). The RESS parameters were drug load (2-50 g), pressure (15-42 MPa) and temperature (40-60°C) in the extraction and pressure in the expansion (0.1-5 MPa) chambers in batch or continuous and CO₂ flow rate in the continuous mode of operation. Particles were characterized for size (laser diffractometry, optical and electronic microscopies-19-61 μm), surface area (BET-0.282-0.423 m²/g), density (pycnometry-1.273-1.358 g/cm³) and yield (2-70%). Extrudates were characterized for the force of extrusion (4 kN), release of coumarin (100%/24 h) and mechanical properties (bending strength and stiffness increased, whereas elasticity decreased in storage) and X-ray diffractometry (micronized particles and extrudates have shown identical patterns) and calorimetry (DSC, enthalpies increased on storage). In the discontinuous mode of operation, increased loads in the extraction or increased pressure in the expansion chambers led to larger particles, whereas increased temperature and pressure in the extraction chamber led to smaller particles. In the continuous mode of operation, a decrease on the expansion pressure, load and CO₂ flow rate led to increased yields. An increase on the flow rate led to a decrease on the particles' diameter, but an increase on coumarin load in the extraction chamber led to an increase in diameter. The study has identified the key parameters in RESS continuous and discontinuous modes of operation affecting the properties of the micronized coumarin particles and has proved the ability of extrudates with a laminar shape on delivering micronized particles.

On the origin of surface imposed anisotropic growth of salicylic and acetylsalicylic acids crystals during droplet evaporation

In this paper droplet evaporative crystallization of salicylic acid (SA) and acetylsalicylic acid (ASA) crystals on different surfaces, such as glass, polyvinyl alcohol (PVA), and paraffin was studied. The obtained crystals were analyzed using powder X-ray diffraction (PXRD) technique. In order to better understand the effect of the surface on evaporative crystallization, crystals deposited on glass were scraped off. Moreover, evaporative crystallization of a large volume of solution was performed. As we found, paraffin which is non-polar surface promotes formation of crystals morphologically similar to those obtained via bulk evaporative crystallization. On the other hand, when crystallization is carried out on the polar surfaces (glass and PVA), there is a significant orientation effect. This phenomenon is manifested by the reduction of the number of peaks in PXRD spectrum recorded for deposited on the surface crystals. Noteworthy, reduction of PXRD signals is not observed for powder samples obtained after scraping crystals off the glass. In order to explain the mechanism of carboxylic crystals growth on the polar surfaces, quantum-chemical computations were performed. It has been found that crystal faces of the strongest orientation effect can be characterized by the highest surface densities of intermolecular interactions energy (IIE). In case of SA and ASA crystals formed on the polar surfaces the most dominant faces are characterized by the highest adhesive and cohesive properties. This suggests that the selection rules of the orientation effect comes directly from surface IIE densities.

Simultaneous formation and micronization of pharmaceutical cocrystals by rapid expansion of supercritical solutions (RESS)

PURPOSE

We investigated the RESS process as a means of simultaneous micronization and cocrystallization of a model drug with poor aqueous solubility.

METHODS

1:1 cocrystals of ibuprofen (IBU) and nicotinamide (NA) were produced with a pilot scale unit for RESS processing.IBU and NA were dissolved in scCO2 at 30 MPa and 50°C. After 24 h, the supercritical solution was expanded at a medium CO2 flow rate of 3.8 kg/h during 60 min into an expansion vessel kept at ambient conditions. Cocrystals were identified with DSC, XRD and confocal Raman microscopy (CRM) and further characterized by SEM, specific surface area, wetting ability, solubility and dissolution testing.

RESULTS

Judging by DSC, XRD and CRM, cocrystals with high purity could be produced with the RESS technique. Micronization via RESS was successful, since the specific surface area of RESS cocrystals was increased almost tenfold in comparison to cocrystals produced by slow solvent evaporation. Due to the additional micronization, the mean dissolution time of IBU from RESS cocrystals was decreased.

CONCLUSIONS

RESS cocrystallization offers the advantage of combining micronization and cocrystallization in a single production step. For drugs with dissolution-limited bioavailability, RESS cocrystallization may therefore be a superior approach in comparison to established cocrystallization techniques.

A NEW SIMPLE CORRELATION FOR CALCULATING SOLUBILITY OF DRUGS IN SUPERCRITICAL CARBON DIOXIDE

During the past 20 years, supercritical fluid (SCF) based technologies have been gaining an increasing attention through the academic and industrial communities due to its advantages. One of the most important parameter for any supercritical-based technologies is the knowledge of the solute solubility at different pressures and temperatures. But, due to several concerns e.g. time and expense, measuring the solubility of all compounds in wide ranges of temperature and pressure is not possible. Respect to this, a new empirical correlation with four fitting parameters has been proposed to correlate the solubility of pharmaceuticals in different temperatures and pressures. The obtained results compared with four widely used density based correlations including Mendez-Santiago and Teja (MST), Bartle et al., Chrastil, Kumar and Johnston (KJ) revealed rather good capability of the proposed simple correlation for predicting the solubility of solutes in supercritical carbon dioxide (SC- CO 2). At last, the obtained results compared with the results of three Equations of State (EoS's) with three different mixing rules.