Screening design of experiment applied to the supercritical antisolvent precipitation of quercetin

Preparation of curcumin submicron particles by supercritical antisolvent method with external adjustable annular gap nozzle

The supercritical antisolvent (SAS) method can effectively improve the bioavailability of poorly water-soluble drugs. However, the current supercritical equipment and processes were not fully developed, making industrialization difficult to achieve. Therefore, an externally adjustable annular gap nozzle and its supporting equipment were designed. Curcumin was used as a model drug, ethanol as the solvent, and supercritical carbon dioxide (SC-CO2) as the antisolvent. Building on single-factor experiments, a Box-Behnken Design-Response Surface Methodology (BBD-RSM) was employed to systematically investigate the effects of four process parameters-crystallizer pressure (12-16 MPa), crystallizer temperature (313-323 K), solution concentration (1-2 mg/mL), and CO2/solution flow rate ratio (133-173 g/g)-on the morphology and particle size of curcumin particles. Using scanning electron microscopy (SEM) and dynamic light scattering (DLS) analyses, morphologies and mean diameter ranges were examined. To look into how the SAS process affects TML's chemical and physical characteristics, X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FT-IR) were further performed. Experimental results show that, flow ratio of CO2/solution had the greatest effect of particle size, followed by crystallizer temperature and solution concentration, while crystallizer pressure had the least influence. The optimum process conditions are operational conditions were set with a crystallizer pressure of 15 MPa, crystallizer temperature of 320 K, solution concentration of 1.2 mg/mL, and flow ratio of CO2/solution of 134 g/g, resulting in curcumin submicron particles with an average particle size of 808 nm being obtained. This study demonstrated the feasibility of an externally adjustable annular gap nozzle and its associated equipment in the SAS process, showcasing significant potential for reducing particles size and enhancing the bioavailability of poorly water-soluble drugs.

Particulate atomisation design methods for the development and engineering of advanced drug delivery systems: A review

The role and opportunities presented by particulate technologies (due to novel processing methods and advanced materials) have multiplied over the last few decades, leading to promising and ideal properties for drug delivery. For example, the dissolution and bioavailability of poorly soluble drug substances and achieving site- specific drug delivery with a desired release profile are crucial aspects of forming (to some extent) state-of-the-art platforms. Atomisation techniques are intended to achieve efficient control over particle size, improved processing time, improved drug loading efficiency, and the opportunity to encapsulate a broad range of viable yet sensitive therapeutic moieties. Particulate engineering through atomization is accomplished by employing various mechanisms such as air, no air, centrifugal, electrohydrodynamic, acoustic, and supercritical fluid driven processes. These driving forces overcome capillary stresses (e.g., liquid viscosity, surface tension) and transform formulation media (liquid) into fine droplets. More frequently, solvent removal, multiple methods are included to reduce the final size distribution. Nevertheless, a thorough understanding of fluid mechanics, thermodynamics, heat, and mass transfer is imperative to appreciate and predict outputs in real time. More so, in recent years, several advancements have been introduced to improve such processes through complex particle design coupled with quality by-design (QbD) yielding optimal particulate geometry in a predictable manner. Despite these valuable and numerous advancements, atomisation techniques face difficulty scaling up from laboratory scales to manufacturing industry scales. This review details the various atomisation techniques (from design to mechanism) along with examples of drug delivery systems developed. In addition, future perspectives and bottlenecks are provided while highlighting current and selected seminal developments in the field.

Current Treatments for COVID-19: Application of Supercritical Fluids in the Manufacturing of Oral and Pulmonary Formulations

Even though more than two years have passed since the emergence of COVID-19, the research for novel or repositioned medicines from a natural source or chemically synthesized is still an unmet clinical need. In this review, the application of supercritical fluids to the development of novel or repurposed medicines for COVID-19 and their secondary bacterial complications will be discussed. We envision three main applications of the supercritical fluids in this field: (i) drug micronization, (ii) supercritical fluid extraction of bioactives and (iii) sterilization. The supercritical fluids micronization techniques can help to improve the aqueous solubility and oral bioavailability of drugs, and consequently, the need for lower doses to elicit the same pharmacological effects can result in the reduction in the dose administered and adverse effects. In addition, micronization between 1 and 5 µm can aid in the manufacturing of pulmonary formulations to target the drug directly to the lung. Supercritical fluids also have enormous potential in the extraction of natural bioactive compounds, which have shown remarkable efficacy against COVID-19. Finally, the successful application of supercritical fluids in the inactivation of viruses opens up an opportunity for their application in drug sterilization and in the healthcare field.

Characterization of excipients to improve pharmaceutical properties of sirolimus in the supercritical anti-solvent fluidized process

Enhanced drug release and bioavailability of poorly soluble active pharmaceutical ingredient (API) can be achieved via a fluidized bed coating integrated with supercritical anti-solvent (SAS-FB) - a process of precipitating drug particles onto carrier granules. However, in the absence of excipients, SAS-FB often results in crystalline of the API on the surface of carriers, limiting the improvement of pharmaceutical properties. Co-processing with excipients is considered an effective approach to improve drug release in the SAS-FB process. Our study used sirolimus, an immune suppressive agent, as the model API to characterize excipients for their effect on pharmaceutical properties in the SAS-FB process. We show that co-precipitation of excipients and sirolumus impacts on carrier specific surface area and drug yield. Among the tested excipients, formulation containing polyvinylpyrrolidone K30 achieved the highest drug yield. Importantly, compared with Rapamune® tablet, our optimized formulation displayed a superior in vivo oral bioavailability by 3.05-fold in Sprague-Dawley rats and 3.99-fold in beagle dogs. A series of characterization of the processed API was performed to understand the mechanism by which excipients contributed to drug dissolution properties. Our study provides a useful guidance for the use of excipients in the SAS-FB technology to improve pharmaceutical properties of sirolimus and other poorly soluble drugs.

Supercritical Antisolvent Process for Pharmaceutical Applications: A Review

The supercritical antisolvent (SAS) technique has been widely employed in the biomedical field, including drug delivery, to obtain drug particles or polymer-based systems of nanometric or micrometric size. The primary purpose of producing SAS particles is to improve the treatment of different pathologies and to better the patient’s compliance. In this context, many active compounds have been micronized to enhance their dissolution rate and bioavailability. Aiming for more effective treatments with reduced side effects caused by drug overdose, the SAS polymer/active principle coprecipitation has mainly been proposed to offer an adequate drug release for specific therapy. The demand for new formulations with reduced side effects on the patient’s health is still growing; in this context, the SAS technique is a promising tool to solve existing issues in the biomedical field. This updated review on the use of the SAS process for clinical applications provides useful information about the achievements, the most effective polymeric carriers, and parameters, as well as future perspectives.

Deposition of CAP/Antioxidants Systems on Silica Particles Using the Supercritical Antisolvent Process

Supercritical carbon dioxide has been used to deposit co-precipitates of natural antioxidants with a polymer onto silica microparticles. The supercritical antisolvent process (SAS) was carried out with the antioxidants by introducing the silica microparticles into the precipitator vessel. Two different configurations were employed to pump the solution. In one configuration, the antioxidant and the polymer were dissolved and injected together through a nozzle. In the second configuration, the antioxidant and the polymer were dissolved in different solutions and sprayed through different nozzles. The use of operating conditions significantly above the critical point (180 bar and 323 K) led to the formation of composites made up of co-precipitates and silica. Delivery profiles showed that the presence of the polymer and the silica delayed release of the antioxidant into gastric media, thus protecting it and allowing its full delivery to the intestinal fluids to improve the effectiveness of the antioxidant.

Recrystallization and Production of Spherical Submicron Particles of Sulfasalazine Using a Supercritical Antisolvent Process

In this study, the recrystallization and production of spherical submicron particles of sulfasalazine, an active pharmaceutical ingredient (API), were performed using the supercritical antisolvent (SAS) process, a nonconventional crystallization technique. Sulfasalazine was dissolved in tetrahydrofuran (THF), and supercritical carbon dioxide (CO2) served as the antisolvent. The effects of operating parameters on the SAS process, including the operating pressure, solution concentration, solution flowrate, CO2 flowrate, and spraying nozzle diameter, at two operating temperatures were examined. The solid-state characteristics of sulfasalazine before and after the SAS process, including particle size, crystal habit, and crystal form, were analyzed using a scanning electron microscope (SEM), powder X-ray diffractometer (PXRD), and differential scanning calorimeter (DSC). A higher operating temperature, intermediate operating pressure, higher CO2 flowrate, and lower solution flowrate are recommended to obtain spherical particles of sulfasalazine. The effects of the solution concentration and spraying nozzle diameter on the SAS process were negligible. Under optimal conditions, spherical sulfasalazine crystals with a mean size of 0.91 μm were generated, and this study demonstrated the feasibility for tuning the solid-state characteristics of API through the SAS process.