Spray Freeze-Drying for inhalation application: Process and Formulation Variables

CFD modelling and simulations of atomization-based processes for production of drug particles: A review

Atomization-based techniques are widely used in pharmaceutical industry for production of fine drug particles due to their versatility and adaptability. Key performance measure of such techniques is their ability to provide control over critical quality attributes (CQAs) of produced drug particles. CQAs of drug particles produced via atomization critically depend on fluid dynamics of sprays; resulting mixing, heat and mass transfer; distribution of supersaturation and subsequent nucleation and growth of particles. It is essential to develop and use computational fluid dynamics (CFD) models for adequate understanding of multi-scale transport processes ranging from molecular scale mixing and particle scale processes, and from atomizer nozzle to overall spray chamber scale establishing relationships between CQAs and design and operating parameters of spray nozzle and chamber. In this work, we critically review past and current research efforts on CFD modelling of pharmaceutical atomization-based processes with an objective to provide clear assessment of the state of the art and to provide recommendations. An overview of the key atomization-based methods for producing drug particles with desired CQAs is presented. Key underlying physical processes and relevant concepts are then outlined. This discussion is related to the demands on CFD models; and state of the art is then discussed with respect to the process needs. Recommendations are provided towards higher fidelity and more efficient models of atomized multiphase flow dynamics and turbulence, drying modelling for the produced particles, and validation approaches. We conclude by highlighting a perceived need for numerical atomization studies with a pharmaceutical context; then, we deliver an outlook on current promising active control and machine learning strategies to augment the shift towards quality-by-design approaches in pharmaceutical manufacturing.

Formulation strategies, preparation methods, and devices for pulmonary delivery of biologics

Biological products, including vaccines, blood components, and recombinant therapeutic proteins, are derived from natural sources such as humans, animals, or microorganisms and are typically produced using advanced biotechnological methods. The success of biologics, particularly monoclonal antibodies, can be attributed to their favorable safety profiles and target specificity. However, their large molecular size presents significant challenges in drug delivery, particularly in overcoming biological barriers. Pulmonary delivery has emerged as a promising route for administering biologics, offering non-invasive delivery with rapid absorption, high systemic bioavailability, and avoidance of first-pass metabolism. This review first details the anatomy and physiological barriers of the respiratory tract and the associated challenges of pulmonary drug delivery (PDD). It further discusses innovations in PDD, the impact of particle size on drug deposition, and the use of secondary particles, such as nanoparticles, to enhance bioavailability and targeting. The review also explains various devices used for PDD, including dry powder inhalers (DPIs) and nebulizers, highlighting their advantages and limitations in delivering biologics. The role of excipients in improving the stability and performance of inhalation products is also addressed. Since dry powders are considered the suitable format for delivering biomolecules, particular emphasis is placed on the excipients used in DPI development. The final section of the article reviews and compares various dry powder manufacturing methods, clarifying their clinical relevance and potential for future applications in the field of inhalable drug formulation.

Advancement and Innovations in Drying of Biopharmaceuticals, Nutraceuticals, and Functional Foods

Drying is a crucial unit operation within the functional foods and biopharmaceutical industries, acting as a fundamental preservation technique and a mechanism to maintain these products' bioactive components and nutritional values. The heat-sensitive bioactive components, which carry critical quality attributes, necessitate a meticulous selection of drying methods and conditions backed by robust research. In this review, we investigate challenges associated with drying these heat-sensitive materials and examine the impact of various drying methods. Our thorough research extensively covers ten notable drying methods: heat pump drying, freeze-drying, spray drying, vacuum drying, fluidized bed drying, superheated steam drying, infrared drying, microwave drying, osmotic drying, vacuum drying, and supercritical fluid drying. Each method is tailored to address the requirements of specific functional foods and biopharmaceuticals and provides a comprehensive account of each technique's inherent advantages and potential limitations. Further, the review ventures into the exploration of combined hybrid drying techniques and smart drying technologies with industry 4.0 tools such as automation, AI, machine learning, IoT, and cyber-physical systems. These innovative methods are designed to enhance product performance and elevate the quality of the final product in the drying of functional foods and biopharmaceuticals. Through a thorough survey of the drying landscape, this review illuminates the intricacies of these operations and underscores their pivotal role in functional foods and biopharmaceutical production.

Spray-freeze-drying as emerging and substantial quality enhancement technique in food industry

Spray freeze drying is an emerging technology in the food industry with numerous applications. Its ability to preserve food quality, maintain nutritional value, and reduce bulk make it an attractive option to food manufacturers. Spray freeze drying can be used to reduce the water content of foods while preserving the shelf life and nutritional value. Spray freeze-drying of food products is a process that involves atomizing food into small droplets and then flash-freezing them. The frozen droplets are then placed in a vacuum chamber and heated, causing the liquid to evaporate and the solid particles to become a dry powder. Spray freeze drying has become a valuable tool for the food industry through its ability to process a wide range of food products. This review's prime focus is understanding spray freeze-dried approaches and emphasizing their applicability in various products.

Screening of Cyclodextrins in the Processing of Buserelin Dry Powders for Inhalation Prepared by Spray Freeze-Drying

Purpose

In this study, we prepared inhalable buserelin microparticles using the spray freeze-drying (SFD) method for pulmonary drug delivery. Raffinose as a cryoprotectant carrier was combined with two levels of five different cyclodextrins (CDs) and then processed by SFD.

Methods

Dry powder diameters were evaluated by laser light scattering and morphology was determined by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis were utilized for the determination of crystalline structures. The aerodynamic properties of the spray freeze-dried powders were evaluated by twin stage impinger (TSI) and the stability of prepared samples was assessed under normal and accelerated conditions.

Results

The prepared powders were mostly porous spheres and the size of microparticles ranged from 9.08 to 13.53 μm, which are suitable as spray-freeze dried particles. All formulations showed amorphous structure confirmed by DSC and XRD. The aerosolization performance of the formulation containing buserelin, raffinose and 5% beta-cyclodextrin (β-CD), was the highest and its fine particle fraction (FPF) was 69.38%. The more circular and separated structures were observed in higher concentrations of CDs, which were compatible with FPFs. The highest stability was obtained in the formulation containing hydroxypropyl beta-cyclodextrin (HP-β-16. CD) 5%. On the contrary, sulfobutylether beta-cyclodextrin (SBE-β-CD) 5% bearing particles showed the least stability.

Conclusion

By adjusting the type and ratio of CDs in the presence of raffinose, the prepared formulations could effectively enhance the aerosolization and stability of buserelin. Therefore, they can be proposed as a suitable career for lung drug delivery.