A Pathway From Porous Particle Technology Toward Tailoring Aerogels for Pulmonary Drug Administration

Particulate platform for pulmonary drug delivery: Recent advances of formulation and fabricating strategies

Pulmonary drug delivery for managing respiratory diseases has attained a significant maturity level and holds substantial potential for applications in treating systemic diseases. Advancements in pulmonary delivery techniques have driven the innovative development of dry powder inhalers (DPIs), specifically engineered to optimize the efficacy of pulmonary drug delivery. This review examines recent progress in formulation and manufacturing strategies of inhalable dry powder, focusing on prescription design and fabrication approaches for advanced particulate systems. These include the integration of cutting-edge excipients into conventional formulations, nano-based delivery system, composite particles, and a blend of traditional and next-generation processing techniques, all contributing to enhanced drug delivery efficiency and bioavailability. Additionally, this review discusses the latest advancements in DPI devices. This review aims to provide a clear perspective on emerging inhalable dry powder formulation and processing trends for pulmonary delivery, highlighting the critical role of novel particulate platform in advancing pulmonary drug delivery systems.

Prediction of Transport and Deposition of Porous Particles in the Respiratory System Using Eulerian-Lagrangian Approach

Deep lung delivery is crucial for respiratory disease treatment. Although nano and submicron particles exhibited a good deposition efficiency in deep regions of the lung, powder nonuniformity and particle agglomeration reduce their efficiency. Inhalation of porous particles (PPs) can overcome the mentioned challenges due to their larger size and low-density. The present study numerically investigates the deposition and penetration efficiency of orally inhaled PPs. A revised drag coefficient was implemented for PP transport. A realistic mouth-throat to the fifth generation of the lung was reconstructed from CT-scan images. A dilute suspension of uniformly distributed particles was considered at three inhalation flow rates (15, 30, and 45 L/min). Governing equations of the flow field and particle transport are solved using an Eulerian-Lagrangian approach. The results demonstrate that inhaling PPs significantly reduces the total and regional deposition of particles. There was also a critical porosity value under moderate and high inhalation flow rates for large PPs. Below this critical value, PP deposition efficiency substantially decreases. Additionally, it was also found that under low inhalation flow rates, the impact of porosity value is negligible. Almost 95% of the PPs penetrate the lower branches. These findings provide particle engineers and pharmaceutics with profound insight into developing novel inhalation techniques and drug delivery methods for deep lung delivery.

Dry powder inhaler design and particle technology in enhancing Pulmonary drug deposition: challenges and future strategies

OBJECTIVES

The efficient delivery of drugs from dry powder inhaler (DPI) formulations is associated with the complex interaction between the device design, drug formulations, and patient's inspiratory forces. Several challenges such as limited emitted dose of drugs from the formulation, low and variable deposition of drugs into the deep lungs, are to be resolved for obtaining the efficiency in drug delivery from DPI formulations. The objective of this study is to review the current challenges of inhaled drug delivery technology and find a way to enhance the efficiency of drug delivery from DPIs.

METHODS/EVIDENCE ACQUISITION

Using appropriate keywords and phrases as search terms, evidence was collected from the published articles following SciFinder, Web of Science, PubMed and Google Scholar databases.

RESULTS

Successful lung drug delivery from DPIs is very challenging due to the complex anatomy of the lungs and requires an integrated strategy for particle technology, formulation design, device design, and patient inhalation force. New DPIs are still being developed with limited performance and future device design employs computer simulation and engineering technology to overcome the ongoing challenges. Many issues of drug formulation challenges and particle technology are concerning factors associated with drug dispersion from the DPIs into deep lungs.

CONCLUSION

This review article addressed the appropriate design of DPI devices and drug formulations aligned with the patient's inhalation maneuver for efficient delivery of drugs from DPI formulations.

Unraveling the Impact of Boron Nitride and Silicon Nitride Nanoparticles on Thermoplastic Polyurethane Fibers and Mats for Advanced Heat Management

The urgent challenges posed by the energy crisis, alongside the heat dissipation of advanced electronics, have embarked on a rising demand for the development of highly thermally conductive polymer composites. Electrospun composite mats, known for their flexibility, permeability, high concentration and orientational degree of conductive fillers, stand out as one of the prime candidates for addressing this need. This study explores the efficacy of boron nitride (BN) and its potential alternative, silicon nitride (SiN) nanoparticles, in enhancing the thermal performance of the electrospun composite thermoplastic polyurethane (TPU) fibers and mats. The 3D reconstructed models obtained from FIB-SEM imaging provided valuable insights into the morphology of the composite fibers, aiding the interpretation of the measured thermal performance through scanning thermal microscopy for the individual composite fibers and infrared thermography for the composite mats. Notably, we found that TPU-SiN fibers exhibit superior heat conduction compared to TPU-BN fibers, with up to a 6 °C higher surface temperature observed in mats coated on copper pipes. Our results underscore the crucial role of arrangement of nanoparticles and fiber morphology in improving heat conduction in the electrospun composites. Moreover, SiN nanoparticles are introduced as a more suitable filler for heat conduction enhancement of electrospun TPU fibers and mats, suggesting immense potential for smart textiles and thermal management applications.

A Review on Micro and Nanoengineering in Powder-Based Pulmonary Drug Delivery

Pulmonary delivery of drugs has emerged as a promising approach for the treatment of both lung and systemic diseases. Compared to other drug delivery routes, inhalation offers numerous advantages including high targeting, fewer side effects, and a huge surface area for drug absorption. However, the deposition of drugs in the lungs can be limited by lung defence mechanisms such as mucociliary and macrophages' clearance. Among the delivery devices, dry powder inhalers represent the optimal choice due to their stability, ease of use, and absence of propellants. In the last decades, several bottom-up techniques have emerged over traditional milling to produce inhalable powders. Among these techniques, the most employed ones are spray drying, supercritical fluid technology, spray freeze-drying, and thin film freezing. Inhalable dry powders can be constituted by micronized drugs attached to a coarse carrier (e.g., lactose) or drugs embedded into a micro- or nanoparticle. Particulate-based formulations are commonly composed of polymeric micro- and nanoparticles, liposomes, solid lipid nanoparticles, dendrimers, nanocrystals, extracellular vesicles, and inorganic nanoparticles. Moreover, engineered formulations including large porous particles, swellable microparticles, nano-in-microparticles, and effervescent nanoparticles have been developed. Particle engineering has also a crucial role in tuning the physical-chemical properties of both carrier-based and carrier-free inhalable powders. This approach can increase powder flowability, deposition, and targeting by customising particle surface features.

Particulate bioaerogels for respiratory drug delivery

The bioaerogel microparticles have been recently developed for respiratory drug delivery and attract fast increasing interests. These highly porous microparticles have ultralow density and hence possess much reduced aerodynamic diameter, which favour them with greatly enhanced dispersibility and improved aerosolisation behaviour. The adjustable particle geometric dimensions by varying preparation methods and controlling operation parameters make it possible to fabricate bioaerogel microparticles with accurate sizes for efficient delivery to the targeted regions of respiratory tract (i.e. intranasal and pulmonary). Additionally, the technical process can provide bioaerogel microparticles with the opportunities of accommodating polar, weak polar and non-polar drugs at sufficient amount to satisfy clinical needs, and the adsorbed drugs are primarily in the amorphous form that potentially can facilitate drug dissolution and improve bioavailability. Finally, the nature of biopolymers can further offer additional advantageous characteristics of improved mucoadhesion, sustained drug release and subsequently elongated time for continuous treatment on-site. These fascinating features strongly support bioaerogel microparticles to become a novel platform for effective delivery of a wide range of drugs to the targeted respiratory regions, with increased drug residence time on-site, sustained drug release, constant treatment for local and systemic diseases and anticipated better-quality of therapeutic effects.

Modern trends in the formulation of microparticles for lung delivery using porogens: methods, principles and examples

Inhalation drug administration is increasingly used for local pharmacotherapy of lung disorders and as an alternative route for systemic drug delivery. Modern inhalation powder systems aim to target drug deposition in the required site of action. Large porous particles (LPP), characterized by an aerodynamic diameter over 5 μm, density below 0.4 g/cm3, and the ability to avoid protective lung mechanisms, come to the forefront of the research. They are mostly prepared by spray techniques such as spray drying or lyophilization using pore-forming substances (porogens). These substances could be gaseous, solid, or liquid, and their selection depends on their polarity, solubility, and mutual compatibility with the carrier material and the drug. According to the pores-forming mechanism, porogens can be divided into groups, such as osmogens, extractable porogens, and porogens developing gases during decomposition. This review characterizes modern trends in the formulation of solid microparticles for lung delivery; describes the mechanisms of action of the most often used porogens, discusses their applicability in various formulation methods, emphasizes spray techniques; and documents discussed topics by examples from experimental studies.

Engineering Inhalable Therapeutic Particles: Conventional and Emerging Approaches

Respirable particles are integral to effective inhalable therapeutic ingredient delivery, demanding precise engineering for optimal lung deposition and therapeutic efficacy. This review describes different physicochemical properties and their role in determining the aerodynamic performance and therapeutic efficacy of dry powder formulations. Furthermore, advances in top-down and bottom-up techniques in particle preparation, highlighting their roles in tailoring particle properties and optimizing therapeutic outcomes, are also presented. Practices adopted for particle engineering during the past 100 years indicate a significant transition in research and commercial interest in the strategies used, with several innovative concepts coming into play in the past decade. Accordingly, this article highlights futuristic particle engineering approaches such as electrospraying, inkjet printing, thin film freeze drying, and supercritical processes, including their prospects and associated challenges. With such technologies, it is possible to reshape inhaled therapeutic ingredient delivery, optimizing therapeutic benefits and improving the quality of life for patients with respiratory diseases and beyond.

Aerogels as Carriers for Oral Administration of Drugs: An Approach towards Colonic Delivery

Polysaccharide aerogels have emerged as a highly promising technology in the field of oral drug delivery. These nanoporous, ultralight materials, derived from natural polysaccharides such as cellulose, starch, or chitin, have significant potential in colonic drug delivery due to their unique properties. The particular degradability of polysaccharide-based materials by the colonic microbiota makes them attractive to produce systems to load, protect, and release drugs in a controlled manner, with the capability to precisely target the colon. This would allow the local treatment of gastrointestinal pathologies such as colon cancer or inflammatory bowel diseases. Despite their great potential, these applications of polysaccharide aerogels have not been widely explored. This review aims to consolidate the available knowledge on the use of polysaccharides for oral drug delivery and their performance, the production methods for polysaccharide-based aerogels, the drug loading possibilities, and the capacity of these nanostructured systems to target colonic regions.

Inhalation powder development without carrier: How to engineer ultra-flying microparticles?

Particle engineering technologies have led to the commercialization of new inhaled powders like PulmoSolTM or PulmoSphereTM. Such platforms are produced by spray drying, a well-known process popular for its versatility, thanks to wide-ranging working parameters. Whereas these powders contain a high drug-loading, we have studied a low-dose case, in optimizing the production of powders with two anti-asthmatic drugs, budesonide and formoterol. Using a Design of Experiments approach, 27 powders were produced, with varying excipient mixes (cyclodextrins, raffinose and maltodextrins), solution concentrations, and spray drying parameters in order to maximize deep lung deposition, measured through fine particle fraction (next generation impactor). Based on statistical analysis, two powders made of hydropropyl-β-cyclodextrin alone or mixed with raffinose and L-leucine were selected. Indeed, the two powders demonstrated very high fine particle fraction (>55%), considerably better than commercially available products. Deep lung deposition has been correlated to very fine particle size and lower microparticles interactions shown by laser diffraction assays at different working pressures, and particle morphometry. Moreover, the two drugs would be predicted to deposit homogeneously into the lung according to impaction studies. Uniform delivery is fundamental to control symptoms of asthma. In this study, we develop carrier-free inhalation powders promoting very efficient lung deposition and demonstrate the high impact of inter-particular interactions intensity on their aerosolization behaviour.

Cyclosporine A-loaded chitosan extra-fine particles for deep pulmonary drug delivery: In vitro and in vivo evaluation

In this study, the extra-fine dry powder inhalers (DPIs) with chitosan (CS) as carrier were successfully prepared by ionic gel method combined with spray drying technique for deep pulmonary drug delivery of Cyclosporine A (CsA), using sodium hyaluronate (SHA) and sodium polyglutamate (SPGA) as polyanions. The CsA-loaded DPIs of CS-SHA-CsA and CS-SPGA-CsA were spherical particles with wrinkles on the surface, which were more conducive to improving the aerosol properties. The aerodynamic evaluation of CS-SHA-CsA and CS-SPGA-CsA showed that the fine particle fraction (FPF) reached up to 79.22 ± 2.12% and 81.55 ± 0.43%, while the emitted fraction (EF) reached 77.15 ± 1.46% and 78.29 ± 2.10%. In addition, the mass median aerodynamic diameter (MMAD) was calculated as 1.58 ± 0.04 μm and 1.94 ± 0.02 μm for CS-SHA-CsA and CS-SPGA-CsA, indicating that they were all extra-fine particles (d < 2 μm). These in vitro aerodynamic results showed that CS-SHA-CsA and CS-SPGA-CsA could reach the smaller airways, further improving therapeutic efficiency. The cell viability on A549 cell line results showed that CS-SHA-CsA and CS-SPGA-CsA were safe to deliver CsA to lungs. The in vivo pharmacokinetics consequence proved that inhalation administration of CS-SHA-CsA and CS-SPGA-CsA could significantly improve the bioavailability of CsA in vivo compared with oral administration of Neoral®, effectively reducing the risk of a series of adverse effects caused by systemic overexposure. In addition, the safety and compatibility of DPIs using SHA, SPGA, and CS as carriers for pulmonary drug delivery was verified by in vivo repeated dose inhalation toxicity. From these findings, the extra-fine DPIs with CS as carrier could be a viable delivery option for the deep pulmonary drug delivery of CsA relative to orally administered drug.

Development of Large Hollow Particles for Pulmonary Delivery of Cyclosporine A

The purpose of this study was to prepare large hollow particles (LHPs) by spray drying for pulmonary delivery of cyclosporine A (CsA), using L-Leucine (LEU) and hydroxypropyl methylcellulose (HPMC) as excipients and ammonium bicarbonate (AB) as a porogen. The prepared LHPs were spherical particles composed of both CsA and LEU on the surface and HPMC on the inner layer. The formulation of CsA-LEU-0.8HPMC-AB as typical LHPs showed excellent in vitro aerodynamic performance with a minimum mass median aerodynamic diameter (MMAD) of 1.15 μm. The solubility of CsA-LEU-0.8HPMC-AB was about 5.5-fold higher than that of raw CsA, and the dissolution of CsA-LEU-0.8HPMC-AB suggested that the drug was released within 1 h. The cell viability of the A549 cell line showed that CsA-LEU-0.8HPMC-AB was safe for delivering CsA to the lungs. In addition, inhalation administration of CsA-LEU-0.8HPMC-AB with the Cmax and AUC0-∞ increasing by about 2-fold and 2.8-fold compared with the oral administration of Neoral® could achieve therapeutic drug concentrations with lower systemic exposure and significantly improve the in vivo bioavailability of CsA. From these findings, the LHPs, with the advantage of avoiding alveolar macrophage clearance, could be a viable choice for delivering CsA by inhalation administration relative to oral administration.

Emerging Trends in Nanotechnology: Aerogel-Based Materials for Biomedical Applications

At present, aerogel is one of the most interesting materials globally. The network of aerogel consists of pores with nanometer widths, which leads to a variety of functional properties and broad applications. Aerogel is categorized as inorganic, organic, carbon, and biopolymers, and can be modified by the addition of advanced materials and nanofillers. Herein, this review critically discusses the basic preparation of aerogel from the sol-gel reaction with derivation and modification of a standard method to produce various aerogels for diverse functionalities. In addition, the biocompatibility of various types of aerogels were elaborated. Then, biomedical applications of aerogel were focused on this review as a drug delivery carrier, wound healing agent, antioxidant, anti-toxicity, bone regenerative, cartilage tissue activities and in dental fields. The clinical status of aerogel in the biomedical sector is shown to be similarly far from adequate. Moreover, due to their remarkable properties, aerogels are found to be preferably used as tissue scaffolds and drug delivery systems. The advanced studies in areas including self-healing, additive manufacturing (AM) technology, toxicity, and fluorescent-based aerogel are crucially important and are further addressed.

Advancements in the Design and Development of Dry Powder Inhalers and Potential Implications for Generic Development

Dry powder inhalers (DPIs) are drug-device combination products where the complexity of the formulation, its interaction with the device, and input from users play important roles in the drug delivery. As the landscape of DPI products advances with new powder formulations and novel device designs, understanding how these advancements impact performance can aid in developing generics that are therapeutically equivalent to the reference listed drug (RLD) products. This review details the current understanding of the formulation and device related principles driving DPI performance, past and present research efforts to characterize these performance factors, and the implications that advances in formulation and device design may present for evaluating bioequivalence (BE) for generic development.

Advanced formulations and nanotechnology-based approaches for pulmonary delivery of sildenafil: A scoping review

Oral sildenafil (SDF) is used to treat pulmonary arterial hypertension (PAH), and its bioavailability is approximately 40%. Several formulations of nano and microparticles (for pulmonary delivery) are being developed because it is possible to improve characteristics such as release time, bioavailability, dose, frequency, and even directly target the drug to the lungs. This review summarizes the latest SDF drug delivery systems for PAH and explains challenges related to the development, the preclinical, and the clinical studies. A scoping review was conducted by searching electronic databases including PubMed, Scopus, and Web of Science to identify studies published between 2001 and 2021. From 300 articles found, 31 met the inclusion criteria. This review identified colloidal formulations such as polymeric, lipid, and metal-organic framework nanoparticles. Strategies were determined to reach the deep airways such as polymeric microparticles, large porous microparticles, nanocomposites, and nano in microparticles. Finally, aspects related to toxicological, pharmacokinetics, and gaps in information for potential use in humans were discussed. SDF formulations are significant candidates for the treatment of PAH by inhalation. In summation, future preclinical studies are still required in large animals, as there is no particular formulation yet submitted to clinical studies.

A Quality by Design Framework for Capsule-Based Dry Powder Inhalers

Capsule-based dry powder inhalers (cDPIs) are widely utilized in the delivery of pharmaceutical powders to the lungs. In these systems, the fundamental nature of the interactions between the drug/formulation powder, the capsules, the inhaler device, and the patient must be fully elucidated in order to develop robust manufacturing procedures and provide reproducible lung deposition of the drug payload. Though many commercially available DPIs utilize a capsule-based dose metering system, an in-depth analysis of the critical factors associated with the use of the capsule component has not yet been performed. This review is intended to provide information on critical factors to be considered for the application of a quality by design (QbD) approach for cDPI development. The quality target product profile (QTPP) defines the critical quality attributes (CQAs) which need to be understood to define the critical material attributes (CMA) and critical process parameters (CPP) for cDPI development as well as manufacturing and control.