Supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM) for micronization of levofloxacin hydrochloride

Solid Dosage Forms of Biopharmaceuticals in Drug Delivery Systems Using Sustainable Strategies

Drug delivery systems (DDS) often comprise biopharmaceuticals in aqueous form, making them susceptible to physical and chemical degradation, and therefore requiring low temperature storage in cold supply and distribution chains. Freeze-drying, spray-drying, and spray-freeze-drying are some of the techniques used to convert biopharmaceuticals-loaded DDS from aqueous to solid dosage forms. However, the risk exists that shear and heat stress during processing may provoke DDS damage and efficacy loss. Supercritical fluids (SCF), specifically, supercritical carbon dioxide (scCO₂), is a sustainable alternative to common techniques. Due to its moderately critical and tunable properties and thermodynamic behavior, scCO₂ has aroused scientific and industrial interest. Therefore, this article reviews scCO₂-based techniques used over the year in the production of solid biopharmaceutical dosage forms. Looking particularly at the use of scCO₂ in each of its potential roles—as a solvent, co-solvent, anti-solvent, or co-solute. It ends with a comparison between the compound’s stability using supercritical CO₂-assisted atomization/spray-drying and conventional drying.

Characterization and Aerosolization Performance of HydroxyPropyl-Beta-Cyclodextrin Particles Produced Using Supercritical Assisted Atomization

In this study, hydroxypropyl-beta-cyclodextrin (HP-β-CD) particles were produced using supercritical assisted atomization (SAA) with carbon dioxide as the spraying medium or co-solute and aqueous ethanol solution as the solvent. The effects of several key factors on the morphology and size of the HP-β-CD particles were investigated. These factors included the solvent effect, temperatures of the precipitator and saturator, concentration of the HP-β-CD solution, and flow rate ratio of carbon dioxide to the HP-β-CD solution. The conducive conditions for producing fine spherical particles were 54.2% (w/w) aqueous ethanol as the solvent; precipitator and saturator temperatures of 373.2 K and 353.2 K, respectively; a flow rate ratio of carbon dioxide to HP-β-CD solution of 1.8; and low concentrations of HP-β-CD solution. The addition of leucine (LEU) enhanced the aerosol performance of the HP-β-CD particles, and the fine particle fraction (FPF) of the HP-β-CD particles with the addition of 13.0 mass% LEU was 1.8 times higher than that of the HP-β-CD particles without LEU. This study shows that LEU can act as a dispersion enhancer and that HP-β-CD particles produced using SAA can be used as pulmonary drug carriers.

Preparation and Characterization of Instant Casein Phosphopeptide by Supercritical Fluid Assisted Atomization

Casein phosphopeptide (CPP) has been widely used as micronutrient supplementation for certain populations. However, its solubility performance is far from satisfying. In this work, instant CPP powders with micropore structures were fabricated by supercritical fluid-assisted atomization (SAA) using supercritical CO₂ fluid (SC-CO₂) as an atomizing agent. The effects of the processing parameters (temperature, time, and pressure) on SC-CO₂ absorption rate and dissolution rate were systematically evaluated and studied. The viscosity of the CPP solution increased with increased pressure of SC-CO₂ as pressure increased its solubility. The processing conditions are optimized as follows: 40 °C, 40 min, and 8.27 MPa, with an SC-CO₂ absorption rate of about 8 wt.%. The dissolution time of the SAA-CPP powders was significantly decreased from 1800 s to 54 s at room temperature, due to the micropore structures and almost 10 times increase in the specific surface area of SAA-CPP. The bioactivities of the instant SAA-CPP, especially the calcium-binding capacity, were also evaluated and showed no observable difference. Among the four CPPs prepared in different ways in this work, SAA-CPP had better dissolution performance. The results show that SAA technology is a promising way to prepare instant polypeptide powders.

Nanoparticles and Nanocrystals by Supercritical CO2-Assisted Techniques for Pharmaceutical Applications: A Review

Many active ingredients currently prescribed show limited therapeutic efficacy, mainly due to their dissolution rate inadequate to treat the pathology of interest. A large drug particle size creates an additional problem if a specific site of action in the human body has to be reached. For this reason, active ingredient size reduction using micronization/nanonization techniques is a valid approach to improve the efficacy of active compounds. Supercritical carbon-dioxide-assisted technologies enable the production of different morphologies of different sizes, including nanoparticles and nanocrystals, by modulating operating conditions. Supercritical fluid-based processes have numerous advantages over techniques conventionally employed to produce nanosized particles or crystals, such as reduced use of toxic solvents, which are completely removed from the final product, ensuring safety for patients. Active compounds can be processed alone by supercritical techniques, although polymeric carriers are often added as stabilizers, to control the drug release on the basis of the desired therapeutic effect, as well as to improve drug processability with the chosen technology. This updated review on the application of supercritical micronization/nanonization techniques in the pharmaceutical field aims at highlighting the most effective current results, operating conditions, advantages, and limitations, providing future perspectives.

Formation of Polyethylene Glycol Particles Using a Low-Temperature Supercritical Assisted Atomization Process

Polyethylene glycol (PEG) particles were prepared using low-temperature supercritical assisted atomization (LTSAA) with carbon dioxide as the spraying medium or the co-solute and acetone as the solvent. The effects of several key factors on the particle size were investigated. These factors included the concentration of the PEG solution, precipitator temperature, saturator temperature, ratio of the volumetric flow rate of carbon dioxide to the PEG solution, and the molecular weight of PEG. Spherical and non-aggregated PEG particles, with a mean size of 1.7-3.2 µm, were obtained in this study. The optimal conditions to produce fine particles were found to be a low concentration of the PEG solution, a low precipitator temperature, and low molecular weight of the PEG. The phase behavior of the solution mixture in the saturator presented a qualitative relationship. At the optimized volumetric flow rate ratios, the composition of CO2 in the feed streams was near the bubble points of the saturator temperatures. X-ray and differential scanning calorimetry analyses indicated that LTSAA-treated PEG had a reduced degree of crystallinity, which could be modulated via the precipitator temperature. PEG microparticles prepared by a LTSAA process would be promising carriers for drug-controlled formulations of PEG-drug composite particles.

Recent Progress of Supercritical Carbon Dioxide in Producing Natural Nanomaterials

Natural medicines are widely utilized in human healthcare. Their beneficial effects have been attributed to the existence of natural active ingredients (NAI) with a positive impact on disease treatment and prevention. Public awareness about the side effects of synthetic chemical compounds increased the need for NAI as well. Clinical applications of NAI are limited by their instability and poor water solubility, while micronization is a major strategy to overcome these drawbacks. Supercritical carbon dioxide (sc-CO2) based nano techniques have drawn great attention in nanomedicinal area for many years, due to their unique characters such as fast mass transfer, near zero surface tension, effective solvents elimination, non-toxic, non-flammable, low cost and environmentally benign. In terms of functions of sc-CO2, many modified sc-CO2 based techniques are developed to produce NAI nanoparticles with high solubility, biological availability and stability. 5 types of promising methods, including gas-assisted melting atomization, CO2-assisted nebulization with a bubble dryer, supercritical fluidassisted atomization with a hydrodynamic cavitation mixer, supercritical CO2-based coating method and solution-enhanced dispersion by sc-CO2 process, are summarized in this article followed by a highlight of their fundamental synthesis principles and important medicinal applications.

A review on recent technologies for the manufacture of pulmonary drugs

This review discusses recent developments in the manufacture of inhalable dry powder formulations. Pulmonary drugs have distinct advantages compared with other drug administration routes. However, requirements of drugs properties complicate the manufacture. Control over crystallization to make particles with the desired properties in a single step is often infeasible, which calls for micronization techniques. Although spray drying produces particles in the desired size range, a stable solid state may not be attainable. Supercritical fluids may be used as a solvent or antisolvent, which significantly reduces solvent waste. Future directions include application areas such as biopharmaceuticals for dry powder inhalers and new processing strategies to improve the control over particle formation such as continuous manufacturing with in-line process analytical technologies.

Supercritical carbon dioxide-based technologies for the production of drug nanoparticles/nanocrystals - A comprehensive review

Low drug bioavailability, which is mostly a result of poor aqueous drug solubilities and of inadequate drug dissolution rates, is one of the most significant challenges that pharmaceutical companies are currently facing, since this may limit the therapeutic efficacy of marketed drugs, or even result in the discard of potential highly effective drug candidates during developmental stages. Two of the main approaches that have been implemented in recent years to overcome poor drug solubility/dissolution issues have frequently involved drug particle size reduction (i.e., micronization/nanonization) and/or the modification of some of the physicochemical and structural properties of poorly water soluble drugs. A large number of particle engineering methodologies have been developed, tested, and applied in the synthesis and control of particle size/particle-size distributions, crystallinities, and polymorphic purities of drug micro- and nano-particles/crystals. In recent years pharmaceutical processing using supercritical fluids (SCF), in general, and supercritical carbon dioxide (scCO₂), in particular, have attracted a great attention from the pharmaceutical industry. This is mostly due to the several well-known advantageous technical features of these processes, as well as to other increasingly important subjects for the pharmaceutical industry, namely their "green", sustainable, safe and "environmentally-friendly" intrinsic characteristics. In this work, it is presented a comprehensive state-of-the-art review on scCO₂-based processes focused on the formation and on the control of the physicochemical, structural and morphological properties of amorphous/crystalline pure drug nanoparticles. It is presented and discussed the most relevant scCO₂, scCO₂-based fluids and drug physicochemical properties that are pertinent for the development of successful pharmaceutical products, namely those that are critical in the selection of an adequate scCO₂-based method to produce pure drug nanoparticles/nanocrystals. scCO₂-based nanoparticle formation methodologies are classified in three main families, and in terms of the most important role played by scCO₂ in particle formation processes: as a solvent; as an antisolvent or a co-antisolvent; and as a "high mobility" additive (a solute, a co-solute, or a co-solvent). Specific particle formation methods belonging to each one of these families are presented, discussed and compared. Some selected amorphous/crystalline drug nanoparticles that were prepared by these methods are compiled and presented, namely those studied in the last 10-15 years. A special emphasis is given to the formation of drug cocrystals. It is also discussed the fundamental knowledge and the main mechanisms in which the scCO₂-based particle formation methods rely on, as well as the current status and urgent needs in terms of reliable experimental data and of robust modeling approaches. Other addressed and discussed topics include the currently available and the most adequate physicochemical, morphological and biological characterization methods required for pure drug nanoparticles/nanocrystals, some of the current nanometrology and regulatory issues associated to the use of these methods, as well as some scale-up, post-processing and pharmaceutical regulatory subjects related to the industrial implementation of these scCO₂-based processes. Finally, it is also discussed the current status of these techniques, as well as their future major perspectives and opportunities for industrial implementation in the upcoming years.

Preparation of micrometric powders of parathyroid hormone (PTH1-34)-loaded chitosan oligosaccharide by supercritical fluid assisted atomization

Parathyroid hormone (PTH1-34)-loaded dry powders were fabricated from aqueous solution for pulmonary administration using supercritical fluid assisted atomization introduced by a hydrodynamic cavitation mixer (SAA-HCM). Herein, chitosan oligosaccharide (CSO) was selected as a carrier in an effort to enhance transmucosal absorption of the drug. Well-defined, separated and spherical PTH(1-34)/CSO composite microparticles were obtained, and the particles size could be well controlled with narrow distribution. Aerodynamic performance was determined using next generation impactor (NGI), and the mass median aerodynamic diameter (MMAD) ranged strictly 1-5 μm range with fine particle fraction (FPF) up to 63.51%. The structural integrity of coprecipitated PTH(1-34) was validated by HPLC, FT-IR and circular dichroism, and a high loading efficiency up to 92.8% was obtained. TGA analyses revealed its thermal stability was preserved and XRD patterns showed amorphous structure of particles. The SAA-HCM process is proposed as a green technique for preparation of inhalable protein/polymer composite dry powders without use of any organic solvents.

Supercritical Fluid Technology: An Emphasis on Drug Delivery and Related Biomedical Applications

During the past few decades, supercritical fluid (SCF) has emerged as an effective alternative for many traditional pharmaceutical manufacturing processes. Operating active pharmaceutical ingredients (APIs) alone or in combination with various biodegradable polymeric carriers in high-pressure conditions provides enhanced features with respect to their physical properties such as bioavailability enhancement, is of relevance to the application of SCF in the pharmaceutical industry. Herein, recent advances in drug delivery systems manufactured using the SCF technology are reviewed. We provide a brief description of the history, principle, and various preparation methods involved in the SCF technology. Next, we aim to give a brief overview, which provides an emphasis and discussion of recent reports using supercritical carbon dioxide (SC-CO2 ) for fabrication of polymeric carriers, for applications in areas related to drug delivery, tissue engineering, bio-imaging, and other biomedical applications. We finally summarize with perspectives.

Dense CO₂ as a Solute, Co-Solute or Co-Solvent in Particle Formation Processes: A Review

The application of dense gases in particle formation processes has attracted great attention due to documented advantages over conventional technologies. In particular, the use of dense CO₂ in the process has been subject of many works and explored in a variety of different techniques. This article presents a review of the current available techniques in use in particle formation processes, focusing exclusively on those employing dense CO₂ as a solute, co-solute or co-solvent during the process, such as PGSS (Particles from gas-saturated solutions^®), CPF (Concentrated Powder Form^®), CPCSP (Continuous Powder Coating Spraying Process), CAN-BD (Carbon dioxide Assisted Nebulization with a Bubble Dryer^®), SEA (Supercritical Enhanced Atomization), SAA (Supercritical Fluid-Assisted Atomization), PGSS-Drying and DELOS (Depressurization of an Expanded Liquid Organic Solution). Special emphasis is given to modifications introduced in the different techniques, as well as the limitations that have been overcome.

Supercritical fluid assisted atomization introduced by an enhanced mixer for micronization of lysozyme: Particle morphology, size and protein stability

Supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM) was used to produce lysozyme microparticles with controlled particle size distribution in the range for aerosol drug delivery. The process is based on the atomization effect of carbon dioxide. The solubilization of certain amount of carbon dioxide in the solution plays the key role and the HCM can intensify mass transfer between carbon dioxide and liquid feedstock greatly. Water was used as the solvent to solubilize lysozyme and thus no organic residual was detected. The influences of process parameters on particle formation were investigated including temperature in the precipitator, pressure and temperature in the mixer, concentration of the solution and feed ratio CO(2)/solution. The particles were characterized with respect to their morphologies and particle size: well defined, spherical and separated particles with diameters ranging between 0.2 and 5μm could be always produced at optimum operating conditions. Bio-activity assay showed that good activity maintenance of higher than 85% for lysozyme was usually achieved. Solid state characterizations were further performed to investigate the changes of lysozyme in the process. Fourier transform infrared spectroscopy indicated that no change in secondary structure had occurred for processed lysozyme. X-ray diffraction analysis showed that the lysozyme particles produced remained similarly amorphous as the raw material. Differential scanning calorimetry and thermogravimetry analysis revealed that there was no significant difference in water association but with the increase of water content after processing.