The Optimisation of Carrier Selection in Dry Powder Inhaler Formulation and the Role of Surface Energetics

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.

Advanced Manufacturing Methods for High-Dose Inhalable Powders

Pulmonary drug delivery is governed by three main categories of forces: interparticle forces in the powder formulation, the dispersion forces during inhalation by the device, and deposition forces in the lungs. The interaction between fine inhalable powder particles of the active ingredient is governed by various types of forces, such as capillary forces, electrostatic forces, and van der Waals forces. The different types of inter-particle interactions influence the balance between powder dispersibility and agglomerate stability. The high level of cohesion forces arising from high surface energy of very fine powder hinders powder flowability, leading to issues of agglomeration. Therefore, there is a critical need for advanced manufacturing techniques to overcome the challenges of handling and manufacture of fine cohesive particles, particularly high-dose powders for inhalation. This review will focus on the challenges facing the formulation process of very fine inhalable powder, the various types of existing particle engineering techniques for high-dose powder inhalers, and the characterization techniques employed to analyse the powder characteristics required to meet the acceptance criteria of inhalable preparations.

Inhaled Dry Powder of Antiviral Agents: A Promising Approach to Treating Respiratory Viral Pathogens

Inhaled dry powder formulations of antiviral agents represent a novel and potentially transformative approach to managing respiratory viral infections. Traditional antiviral therapies in the form of tablets or capsules often face limitations in terms of therapeutic activity, systemic side effects, and delayed onset of action. Dry powder inhalers (DPIs) provide a targeted delivery system, ensuring the direct administration of antivirals to the infection site, the respiratory tract, which potentially enhance therapeutic efficacy and minimize systemic exposure. This review explores the current state of inhaled dry powder antiviral agents, their advantages over traditional routes, and specific formulations under development. We discuss the benefits of targeted delivery, such as improved drug deposition in the lungs and reduced side effects, alongside considerations related to the formulation preparation. In addition, we summarize the developed (published and marketed) inhaled dry powders of antiviral agents.

Preparation, characterisation and pharmacokinetics evaluation of dry power inhalation formulations of polymyxin B

This study aims to develop an alternative and effective drug delivery system through inhalation therapy to address the limitations of polymyxin B (PMB) intravenous treatment for pneumonia. PMB dry powder inhalers (DPIs) were prepared and characterized. The in vitro lung deposition and antibacterial efficacy were also assessed. To compare the systemic exposure following changes in administration routes, blood concentration measurements were conducted for different routes of administration spherical PMB particles, measuring 3 microns in diameter, achieved the highest fine particle fraction (FPF) of 53%. When particles transition from regular shapes to irregular blocks, a decrease of 1 micron in particle size resulted in an approximate 20% increase in FPF. Moreover, the FPF of PMB particles combined with smooth-surfaced lactose was approximately 10% less than that of PMB particles combined with rough-surfaced mannitol. The bioavailability of PMB DPI reached a peak of 77.46% within 10 min. In a murine model of acute lung infection, treatment with PMB DPI significantly reduced the bacterial load in lung tissues compared to the control group with intravenous PMB administration. In summary, particles with reduced size and increased sphericity displayed a greater FPF led to enhanced therapeutic efficacy and safety.

Cannabidiol and Hydroxypropyl-β-Cyclodextrin for the Development of Deflated Spherical-Shaped Inhalable Powder

In addition to the known therapeutic indications for cannabidiol, its administration by inhalation appears to be of great interest. Indeed, there is evidence of cannabidiol's efficacy in several physiological pathways, suggesting its potential for a wide range of applications for both local and systemic pulmonary administration like cancers. Significant advances in pulmonary drug delivery have led to innovative strategies to address the challenges of increasing the respirable fraction of drugs and standardizing inhalable products. Among different devices, dry powder inhalers offer significant advantages including high stability and ease of use. Particle engineering using techniques such as spray drying is now the focus of research and is expected to improve upon, rather than completely replace, traditional carrier-based formulations. The development of carrier-free powders (without lactose-carrier) is mainly used for medicines with low active ingredient doses, which limits the technology. Previously, we demonstrated the benefits of using a cyclodextrin to obtain deflated spherical-shaped powders by spray drying. In this study the potential of this excipient with a very poorly water-soluble active molecule was investigated. Inhalable cannabidiol powders were developed by spray drying, using the solubility enhancers hydroxypropyl-beta-cyclodextrin and ethanol to optimize cannabidiol water-solubility. Electron microscopy images revealed consistent deflated spherical shapes, while particle size analysis showed low polydispersity and suitable sizes for deep lung deposition (2 µm). The selected engineered powders (without ethanol) had very high fine particle fractions (> 60%) due to their deflated surface. Finally, the powder was instantly solubilized leading to drug dissolution, which is important for therapeutic efficacy. In conclusion, this study successfully develops a cannabidiol inhalation powder by particle engineering having suitable aerosolization behavior. Due to the speed of the process and the performance of the finished product, this work opens the door for future studies. It has been shown that active molecules that are only slightly soluble in water can be formulated effectively as a powder for inhalation. Other molecules could be tested and subsequent in vivo studies conducted to demonstrate correlation with these in vitro results.

Optimization of Carrier-Based Dry Powder Inhaler Performance: A Review

Dry powder inhalers (DPI's) are becoming increasingly popular due to growing interest in pulmonary drug delivery and their performance is the net result of a series of processes carried out during the formulation development and manufacturing process such as excipient selection, blending, milling, filling, and spray drying. To reach the small airways of the deep lung, the active pharmaceutical ingredients (API) particles need to have an aerodynamic diameter of 1-5 μm to avoid impaction and particle sedimentation in the upper respiratory tract, and due to this small particle size, the powder becomes highly cohesive resulting in poor flow. Therefore, API is usually blended with a coarse carrier to improve flowability, and due to its large size, it is more fluidizable than the micronized drug. Carrier-based DPI formulations usually consist of micronized drugs, a coarse carrier, and additional components, such as micronized lactose and force control agents, including magnesium stearate or leucine. Additionally, the manufacturing process of DPIs relies heavily on powder processing technologies, such as the micronization of API, blending, and powder filling. The aerosol performance of a DPI is significantly affected by the selection of formulation components and the processing of the formulation and, therefore, it is crucial to evaluate these parameters. This review will discuss different factors influencing the aerosol performance of carrier-based DPIs, including formulation components, device considerations, and manufacturing parameters. Additionally, novel technologies pertaining to the optimization of DPI performance are also discussed.

Different Carriers for Use in Dry Powder Inhalers: Characteristics of Their Particles

In contemporary times, there has been a rise in the utilization of dry powder inhalers (DPIs) in the management of pulmonary and systemic diseases. These devices underwent a swift advancement in terms of both the equipment utilized and the formulation process. In this review, the carrier physicochemical characteristics that influence DPI performance are discussed, focusing its shape, morphology, size distribution, texture, aerodynamic diameter, density, moisture, adhesive and detachment forces between particles, fine carrier particles, and dry powder aerosolization. To promote the deposition of the active principal ingredient deep within the pulmonary system, advancements have been made in enhancing these factors and surface properties through the application of novel technologies that encompass particle engineering. So far, the most used carrier is lactose showing some advantages and disadvantages, but other substances and systems are being studied with the intention of replacing it. The final objective of this review is to analyze the physicochemical and mechanical characteristics of the different carriers or new delivery systems used in DPI formulations, whether already on the market or still under investigation.

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.

Ternary Dry Powder Agglomerate Inhalation Formulation of Melatonin With Air Jet Mixing to Improve In Vitro And In Vivo Performance

An improved agglomerate formulation with melatonin and fine lactose for dry powder inhalation using Turbuhaler® was developed. Co-grinding lactose with 1 % magnesium stearate prior to air jet mixing served as a key factor to improve the in vitro aerosolization and in vivo efficacy. Elevated mixing pressure facilitated the dispersion and homogenization of the cohesive mixture for even distribution of agglomerate size after spheroidization and subsequent higher emitted dose with lower variation. Magnesium stearate was employed as a tertiary component to adjust the interparticle force for better aerosolization. At optimized mixing pressure, co-grinding lactose with magnesium stearate before jet mixing displayed further improvement of fine particle fraction to 71.6 ± 3.1 %. The superior fine particle deposition efficiency contributed to rapid onset of action and a high bioavailability of 67.0 % after intratracheal administration to rats. Overall, an inhalable melatonin dry powder formulation exhibiting good aerosol property and lung deposition with clinical translation potential was developed.