Dry Powder Inhaler Formulations Research Articles

Design and Evaluation of Dry Powder Inhalation Formulation for Pulmonary Delivery of Docetaxel: A Novel Approach in Non-Small Cell Lung Cancer

Design and Evaluation of Dry Powder Inhalation Formulation for Pulmonary Delivery of Docetaxel: A Novel Approach in Non-Small Cell Lung Cancer

Impact of protein aggregation on the immunogenicity of a human monoclonal antibody following pulmonary administration in mice

Spray drying is a widely employed method for generating dry powder formulations for inhalation. Yet, it presents substantial challenges when applied to therapeutic proteins due to stability issues. The formation of protein aggregates during the atomization and the heating steps can diminish protein activity and raise immunogenicity concerns. Here, we assessed the impact of varying levels of protein aggregates generated during spray-drying on the fate and the immunogenicity of the human monoclonal antibody NIP228 following intratracheal administration in mice. Aggregate-free rhodamine labelled NIP228 was spray-dried with or without 1% polysorbate 80 surfactant, resulting in the generation of powder formulations with associated low and high protein aggregate levels, respectively. Confocal imaging highlighted the presence of aggregates in the lungs for both powders but not for the solution, while flow cytometry analysis designated alveolar macrophages as the main immune cells taking up rhod-NIP228 in the lungs with very little involvement of dendritic cells and interstitial macrophages following a single dose administration. Notably, repeated intratracheal administration of the three formulations in mice did not impact the magnitude of the anti-drug antibody response in sera or broncho-alveolar lavages. The pulmonary route appeared to evoke a more robust immune response when compared to subcutaneous administration. Overall, the level of NIP228 aggregation in this study did not appear to be the primary driver of NIP228 immunogenicity following delivery to the lungs in mice, shedding new light on the interplay between protein aggregation and immunogenicity in the context of the pulmonary delivery of therapeutic proteins.

Effect of lubricants type and particle size on the rheological properties and aerosolization behavior of dry powder inhalers

A commonly used strategy to improve aerosolization behavior of carrier-based dry powder inhalers (DPIs) is the addition of magnesium stearate as a lubricant, yet it may also negatively affect properties of DPIs. Thus, the aim of this study was to find lubricants that could be used as alternatives of magnesium stearate and meanwhile verify the applicability of using powder rheological properties to predict the performance of different lubricants in DPIs. Here, using fluticasone propionate as a model drug, LH200 as the carrier, influence of lubricants type and particle size, including magnesium stearate, sodium stearate, Leucine, sodium stearate fumarate, Compritol® 888 ATO, and Compritol® HD5 ATO, on the physicochemical properties, powder rheology and aerosolization behavior of the DPI formulations was characterized. Further, the relationship between powder rheological parameters and in-vitro drug deposition parameter, fine particle fraction (FPF), were explored, and the contribution of powder flowability and adhesion was evaluated using principal component analysis (PCA). The results showed that magnesium stearate, sodium stearate and smaller sized leucine significantly reduced the basic flowability energy, aeration energy and Permeability of the DPI formulations, leading to improved aerosolization behavior. A robust linear correlation was established between rheological parameters and FPF. PCA showed that in lubricants containing formulations, the contribution of flowability (74.69%) was greater than that of adhesion (25.31%). In conclusion, sodium stearate and smaller particle size Leucine can be considered as substitutes of magnesium stearate in DPI formulations.

Feasibility of a High-Dose Inhaled Indomethacin Dry Powder with Dual Deposition for Pulmonary and Oral Delivery

In this study we have developed a high-dose dry powder inhaler formulation of indomethacin using a novel approach to carrier-based formulations. Specifically, larger drug particles serve as the carrier for the smaller micronized drug particles, such that an inhaled dose is combined with an oral dose. To study this system, the aerosol performance of a standard indomethacin–lactose formulation was compared to carrier-free micronized indomethacin and a drug-as-carrier formulation (a micronized indomethacin–coarse indomethacin blend). Indomethacin with lactose showed a very poor aerosol performance, indicating high adhesion between the drug and carrier. The performance of the carrier-free micronized drug was significantly better, indicating low cohesion. Coarse drug particles as a carrier allowed improved powder flow and aerosol performance while also providing a potential secondary route of absorption of indomethacin, namely oral. An optimal formulation ratio of 1:1 (w/w) fine indomethacin–coarse indomethacin was developed in this study.

Evaluating drug distribution in rat lung by mass spectrometry imaging after dry powder insufflation: Comparison of jet-milling, spray-drying, and thin film freezing

Uniform drug distribution within lungs is crucial for effective treatment of lung diseases when delivered via the pulmonary route. Imaging techniques such as gamma scintigraphy, positron emission tomography, and single-photon emission computed tomography, and others, have limitations, including the need for tagging, product reformulation, and in vitro validation. Mass Spectrometry Imaging (MSI) overcomes these drawbacks by visualizing drug distribution within lungs without tagging. In this study, voriconazole dry powder formulations for inhalation were prepared by three different methods: jet-milling, spray-drying, and thin film freezing (TFF). MSI was used to differentiate voriconazole distribution in rat lung after dry powder insufflation. The TFF-processed voriconazole powder, consisting of brittle, easily shearable nanoaggregates, exhibited the most homogeneous distribution in lung tissue, with the lowest airway-to-lung voriconazole deposition ratio (1.27), followed by spray-dried (1.76) and jet-milled (2.73). This enhanced distribution is attributed to the smaller particle size after disaggregation and rapid movements on the liquid surface. The results suggest that TFF dry powders for inhalation can enhance treatment efficiency and reduce toxicity for lung diseases, further supporting TFF as a promising method to formulate powder for pulmonary drug delivery.

Synergistic effect of magnesium stearate and fine lactose in improving aerosolization performance of fluticasone propionate in dry powder formulation

Magnesium stearate (MgSt) and lactose fines are often used as ternary components in carrier-based dry powder inhalers (DPIs) to improve fine particle fraction (FPF), but whether they act synergistically to improve aerosolization performance of DPI formulations is currently less studied. In addition, the applicability of utilizing powder rheological parameters to predict the FPF needs to be further verified. Thus, in this study, using fluticasone propionate (FP) as a model drug, effect of lactose fines addition in 0.5% MgSt containing DPI formulations on their powder and aerodynamic properties was explored. Influence of MgSt and fines mixing order on the DPIs performance was also investigated. The results showed that addition of lactose fines (1–10%) in 0.5% MgSt containing formulations could further improve flowability and enhance adhesion of the mixtures, and they could act synergistically to improve FPF. Moreover, the presence of 0.5% MgSt can greatly reduce the amount of lactose fines required to achieve the comparable FPF. The mixing order can affect distribution of MgSt on the carrier surface, with higher FPF noted when MgSt was mixed with carrier first, followed by lactose fines. A good linear relationship between powder rheological parameters such as basic flowability energy (BFE), Permeability and FPF was disclosed. In conclusion, in FP based DPIs, MgSt and lactose fines act synergistically to enhance FPF by tuning powder characteristics. Good flowability (27.39%) and strong adhesion (72.61%) contributed to the enhanced drug deposition in the lung.

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. [Figure: see text].

Exploration of Nanomedicine-Based Dry Powder Inhalation Formulation Co-Loaded with Erlotinib and Curcumin for Treatment of Non-Small Cell Lung Cancer

Erlotinib is used as first-line chemotherapy for the treatment of non-small cell lung cancer (NSCLC), which accounts for approximately 85% of lung cancers. Curcumin has potential antitumor effects in different types of cancer including NSCLS with additional chemopreventive and radioprotective effects. The aim of the study was to develop erlotinib and curcumin co-loaded dry powder inhalation (EC-DPI) formulation using nanoprecipitation technique with a goal of achieving a stronger cytotoxic effect against A549 cancer cells. The optimized DPI formulation resulted in suitable particle size (313.28 ± 26.19 nm), polydispersity index (0.156 ± 0.016) and zeta potential (29.4 ± 1.22 mV). Carr’s index (6.62 ± 1.43) and Hausner ratio (1.058 ± 0.03) demonstrated excellent flowability of the powder. The fine particle fraction (64.7 ± 7.8%) and mass median aerodynamic diameter (2.98 ± 0.04 [Formula: see text]m) of the optimized formulation revealed good aerosol performance and its suitability for direct delivery to the lungs. In-vitro cytotoxic potential of EC-DPI was determined against A549 cancer cells and compared with curcumin-loaded DPI formulation (C-DPI) and erlotinib-loaded DPI formulation (E-DPI). The IC[Formula: see text] values for E-DPI and C-DPI were found to be 36.6 ± 2.4 [Formula: see text]M and 24.4 ± 2.7 [Formula: see text]M, respectively. The IC[Formula: see text] value for EC-DPI was 20.5 ± 2.1 [Formula: see text]M confirming the synergistic effect of both drugs against A549 cancer cells. The internalization of the drug inside A549 cells was detected by a cellular uptake study. The EC-DPI demonstrated the highest cellular uptake (0.07 ± 0.006 ng/[Formula: see text]g) followed by the formulation containing curcumin (0.05 ± 0.003 ng/[Formula: see text]g) and erlotinib (0.03 ± 0.004 ng/[Formula: see text]g) alone at the end of 6 h. Hence, the developed DPI formulation can be considered as a potential therapeutic approach for the direct delivery of erlotinib and curcumin to treat NSCLC.

Cocrystal formulation design of 4-Aminosalicylic acid and isoniazid via spray-drying based on a ternary phase diagram toward simultaneous pulmonary delivery

Cocrystal engineering is a potent strategy for enhancing drug properties, but its application in spray-drying has been limited. Furthermore, concurrently introducing two drugs and realizing simultaneous pharmacological effects at the target site is challenging. This is particularly evident for oral formulations designed for systemic use, but the local administration of drugs at the target site displays the potential to overcome this problem. Herein, we investigated the potential of cocrystallization principles for use in developing dry powder inhaler formulations of anti-tuberculosis drugs. We focused on the formation of cocrystals of 4-aminosalicylic acid (PAS) and isoniazid (INH), which are crucial components of tuberculosis treatment. Via spray-drying, we successfully produced spray-dried particles of PAS-INH that exhibited hydrogen bonding interactions between the molecules. Aerosolization performance evaluation with an Andersen Cascade Impactor (ACI) confirmed the concurrent deposition of both drugs, highlighting the potential of our particle design for use in the co-delivery of PAS-INH. Furthermore, simulated lung dissolution studies using the ACI and Transwell inserts revealed synchronized dissolution patterns, indicating promising prospects for use in effective drug delivery. This innovative approach to tuberculosis therapy has significant implications for improving treatment efficacy and enhancing patient adherence, potentially revolutionizing tuberculosis treatment.

Dry Powder Inhaler Formulation of Lactobacillus rhamnosus GG Targeting Pseudomonas aeruginosa Infection in Bronchiectasis Maintenance Therapy.

The inhaled delivery of lactic acid bacteria (LAB) probiotics has been demonstrated to exert therapeutic benefits to the lungs due to LAB's immunomodulatory activities. The development of inhaled probiotics formulation, however, is in its nascent stage limited to nebulized LAB. We developed a dry powder inhaler (DPI) formulation of lactobacillus rhamnosus GG (LGG) intended for bronchiectasis maintenance therapy by spray freeze drying (SFD). The optimal DPI formulation (i.e., LGG: mannitol: lactose: leucine = 35: 45: 15: 5 wt.%) was determined based on the aerosolization efficiency (86% emitted dose and 26% respirable fraction) and LGG cell viability post-SFD (7 log CFU/mL per mg powder). The optimal DPI formulation was evaluated and compared to lyophilized naked LGG by its (1) adhesion capacity and cytotoxicity to human lung epithelium cells (i.e., A549 and 16HBE14o- cells) as well as its (2) effectiveness in inhibiting the growth and adhesion of Pseudomonas aeruginosa to lung cells. The optimal DPI of LGG exhibited similar non-cytotoxicity and adhesion capacity to lung cells to naked LGG. The DPI of LGG also inhibited the growth and adhesion of P. aeruginosa to the lung cells as effectively as the naked LGG. The present work established the feasibility of delivering the LAB probiotic by the DPI platform without adversely affecting LGG's anti-pseudomonal activities.

Cryomilled electrospun nanofiber mats containing d-mannitol exhibit suitable for aerosol delivery of proteins

Dry powder inhalers (DPIs) are the first choice for inhalation drug development. However, some conventional DPI formulation processes require heating, which may damage high molecular weight drugs such as proteins and nucleic acids. In this study, we propose a novel DPI preparation process that avoids the use of heat. Dry powders were prepared by cryomilling nanofiber mats composed of polyvinyl alcohol, D(−)-mannitol (Man), and α-chymotrypsin (α-Chy) as the model drug using the electrospinning method. The addition of Man conferred high dispersibility and excellent in vitro aerosol performance to the nanofiber mat powder in a very short milling time (less than 0.5 min) as assessed using the Andersen cascade impactor. Powders were classified according to the degree of friability, and among these, nanofiber mats containing 15 % Man and milled for 0.25 min exhibited the highest aerosol performance. Nanofiber mats containing Man milled for less than 0.5 min also exhibited greater α-Chy enzymatic activity than a nebulized α-Chy solution. Furthermore, single inhalation induced no significant lung tissue damage as evidenced by lactate dehydrogenase activity assays of mouse bronchoalveolar lavage fluid. This novel DPI formulation process may facilitate the safe and efficient inhalational delivery of therapeutic proteins.

Inhalable Polymeric Microparticles for Phage and Photothermal Synergistic Therapy of Methicillin-Resistant Staphylococcus aureus Pneumonia.

Acute methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is a common and serious lung infection with high morbidity and mortality rates. Due to the increasing antibiotic resistance, toxicity, and pathogenicity of MRSA, there is an urgent need to explore effective antibacterial strategies. In this study, we developed a dry powder inhalable formulation which is composed of porous microspheres prepared from poly(lactic-co-glycolic acid) (PLGA), internally loaded with indocyanine green (ICG)-modified, heat-resistant phages that we screened for their high efficacy against MRSA. This formulation can deliver therapeutic doses of ICG-modified active phages to the deep lung tissue infection sites, avoiding rapid clearance by alveolar macrophages. Combined with the synergistic treatment of phage therapy and photothermal therapy, the formulation demonstrates potent bactericidal effects in acute MRSA pneumonia. With its long-term stability at room temperature and inhalable characteristics, this formulation has the potential to be a promising drug for the clinical treatment of MRSA pneumonia.

Development of Inhaled Tuberculosis Microparticle using Polysaccharide Polymers Containing Rifamycin Groups: In-vitro and In-vivo Study

Tuberculosis (TB) is one of the urgent global health problems. TB therapy involves the use of antibiotics, but unwanted side effects often accompany the treatment of TB with high doses and long periods of time. In an effort to increase the effectiveness of TB treatment and reduce side effects, direct drug delivery to the lungs is the focus of research. One of the approaches used is the development of drug delivery systems that use natural polymers in dry powder inhalation (DPI) formulations. Natural polymers, especially polysaccharides, have various advantages, such as biodegradability, biocompatibility and non-toxicity. This review discusses the use of rifamycin microparticle tuberculosis inhalation using polysaccharide polymers and reviews relevant in-vitro and in-vivo studies. The use of natural polymers, especially polysaccharides, is expected to increase the efficiency of TB therapy by reducing drug doses and systemic side effects and increasing direct drug delivery to infected organs.

Optimizing large porous mannitol-leucine microparticles via spray drying technique

The development of large porous microparticles (LPPs) has gained attention for dry powder in-halation (DPI) formulations due to their potential to enhance the efficiency of drug delivery into the lungs. In this work, large porous mannitol-leucine microparticles (MALs) were developed using a spray drying technique. Mannitol was co-spray dried with ammonium bicarbonate (0–50 % w/w) and leucine (1–20 % w/w). The morphology of MAL particles was spherical hollow with corrugated surface. The MAL with 10 % leucine (MAL-10) showed the lowest bulk density (0.08 g/cm3) with the highest surface area (7.85 m2/g), while the aerodynamic diameter (Daer) was within 1–5 μm, indicating the suitability to penetrate the lung. The DSC and XRD results indicated that the MALs exhibited a mixture of β- and α-polymorphs, while the FT-IR spectra con-firmed that no chemical interaction during co-processing. The leucine co-processing significantly improved powder flowability of the MAL-10 (28.33° for angle of repose). In addition, the co-processing with high leucine concentration (10–20 %) significantly reduced moisture sorption, while the polymorph of MALs did not change after 30 days of hygroscopicity study that indicated good stability. According to all results, the MALs could potentially be applied as drug carriers for DPI formulations.

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

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. 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. 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. 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.

Design of Experiment (DoE) Approach for Developing Inhalable PLGA Microparticles Loaded with Clofazimine for Tuberculosis Treatment.

Tuberculosis (TB) is an airborne bacterial infection caused by Mycobacterium tuberculosis (M. tb), resulting in approximately 1.3 million deaths in 2022 worldwide. Oral therapy with anti-TB drugs often fails to achieve therapeutic concentrations at the primary infection site (lungs). In this study, we developed a dry powder inhalable formulation (DPI) of clofazimine (CFZ) to provide localized drug delivery and minimize systemic adverse effects. Poly (lactic acid-co-glycolic acid) (PLGA) microparticles (MPs) containing CFZ were developed through a single emulsion solvent evaporation technique. Clofazimine microparticles (CFZ MPs) displayed entrapment efficiency and drug loading of 66.40 ± 2.22 %w/w and 33.06 ± 1.45 µg/mg, respectively. To facilitate pulmonary administration, MPs suspension was spray-dried to yield a dry powder formulation (CFZ SD MPs). Spray drying had no influence on particle size (~1 µm), zeta potential (-31.42 mV), and entrapment efficiency. Solid state analysis (PXRD and DSC) of CFZ SD MPs studies demonstrated encapsulation of the drug in the polymer. The drug release studies showed a sustained drug release. The optimized formulation exhibited excellent aerosolization properties, suggesting effective deposition in the deeper lung region. The in vitro antibacterial studies against H37Ra revealed improved (eight-fold) efficacy of spray-dried formulation in comparison to free drug. Hence, clofazimine dry powder formulation presents immense potential for the treatment of tuberculosis with localized pulmonary delivery and improved patient compliance.

Inhalable solid lipid nanoparticles of levofloxacin for potential tuberculosis treatment

Delivering novel antimycobacterial agents through the pulmonary route using nanoparticle-based systems shows promise for treating diseases like tuberculosis. However, creating dry powder inhaler (DPI) with suitable aerodynamic characteristics while preserving nanostructure integrity and maintaining bioactivity until the active ingredient travels deeply into the lungs is a difficult challenge. We developed DPI formulations containing levofloxacin-loaded solid lipid nanoparticles (SLNs) via spray-drying technique with tailored aerosolization characteristics for effective inhalation therapy. A range of biophysical techniques, including transmission electron microscopy, confocal microscopy, and scanning electron microscopy were used to measure the morphologies and sizes of the spray-dried microparticles that explored both the geometric and aerodynamic properties. Spray drying substantially reduced the particle sizes of the SLNs while preserving their nanostructural integrity and enhancing aerosol dispersion with efficient mucus penetration. Despite a slower uptake rate compared to plain SLNs, the polyethylene glycol modified formulations exhibited enhanced cellular uptake in both A549 and NR8383 cell lines. The percent viability of Mycobacterium bovis had dropped to nearly 0 % by day 5 for both types of SLNs. Interestingly, the levofloxacin-loaded SLNs demonstrated a lower minimum bactericidal concentration (0.25 µg/mL) compared with pure levofloxacin (1 µg/mL), which indicated the formulations have potential as effective treatments for tuberculosis.

Fine excipient materials in carrier-based dry powder inhalation formulations: The interplay of particle size and concentration effects

The contributions of fine excipient materials to drug dispersibility from carrier-based dry powder inhalation (DPI) formulations are well recognized, although they are not completely understood. To improve the understanding of these contributions, we investigated the influences of the particle size of the fine excipient materials on characteristics of carrier-based DPI formulations. We studied two particle size grades of silica microspheres, with volume median diameters of 3.31 μm and 8.14 μm, as fine excipient materials. Inhalation formulations, each composed of a lactose carrier material, one of the fine excipient materials (2.5% or 15.0% w/w), and a drug (fluticasone propionate) material (1.5% w/w) were prepared. The physical microstructure, the rheological properties, the aerosolization pattern, and the aerodynamic performance of the formulations were studied. At low concentration, the large silica microspheres had a more beneficial influence on the drug dispersibility than the small silica microspheres. At high concentration, only the small silica microspheres had a beneficial influence on the drug dispersibility. The results reveal influences of fine excipient materials on mixing mechanics. At low concentration, the fine particles improved deaggregation and distribution of the drug particles over the surfaces of the carrier particles. The large silica microspheres were associated with a greater mixing energy and a greater improvement in the drug dispersibility than the small silica microspheres. At high concentration, the large silica microspheres kneaded the drug particles onto the surfaces of the carrier particles and thus impaired the drug dispersibility. As a critical attribute of fine excipient materials in carrier-based dry powder inhalation formulations, the particle size demands robust specification setting.

Developing Dry Powder Inhaler Formulations.

This section aims to provide a concise and contemporary technical perspective and reference resource covering dry powder inhaler (DPI) formulations. While DPI products are currently the leading inhaled products in terms of sales value, a number of confounding perspectives are presented to illustrate why they are considered surprisingly, and often frustratingly, poorly understood on a fundamental scientific level, and most challenging to design from first principles. At the core of this issue is the immense complexity of fine cohesive powder systems. This review emphasizes that the difficulty of successful DPI product development should not be underestimated and is best achieved with a well-coordinated team who respect the challenges and who work in parallel on device and formulation and with an appreciation of the handling environment faced by the patient. The general different DPI formulation types, which have evolved to address the challenges of aerosolizing fine cohesive drug-containing particles to create consistent and effective DPI products, are described. This section reviews the range of particle engineering processes that may produce micron-sized drug-containing particles and their subsequent assembly as either carrier-based or carrier-free compositions. The creation of such formulations is then discussed in the context of the material, bulk, interfacial and ultimately drug-delivery properties that are considered to affect formulation performance. A brief conclusion then considers the future DPI product choices, notably the issue of technology versus affordability in the evolving inhaler market.

Compatibility study of formoterol fumarate-lactose dry powder inhalation formulations: Spray drying, physical mixture and commercial DPIs

Formoterol fumarate (FF) is a long-acting beta-adrenergic receptor agonist that is administered as a dry powder inhaler (DPI) for chronic respiratory conditions. In most DPI formulations, the drug substance and the carrier are the two major components. Lactose is the most common carrier, which can undergo a Maillard reaction in the presence of primary and secondary amines. FF contains a secondary amine. Since the potential for Maillard reaction in DPI formulations has not been investigated yet, this study aims to investigate any potential reaction between lactose and FF. The formulations were prepared using a tubular mixer and spray drying techniques. FF and lactose were blended using a tubular mixer (TM FF-Lac). In the spray drying method, FF and lactose were dissolved in distilled water: MeOH and then spray dried (SD FF-Lac). The samples were stored at both ambient conditions and elevated temperature and humidity (40 °C ± 2, 75% ± 5 RH), and subsequently analyzed to identify any signs of incompatibilities. Differential scanning calorimetry (DSC), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS-MS) were employed for sample analysis. The in vitro aerosolization performance was evaluated using a next-generation impactor (NGI). The results showed that the colour of the DPI formulations changed from white to brown after storage at elevated temperature and humidity. Although the SD FF-Lac had better aerosolization properties, it was more vulnerable to degradation due to its amorphous nature. The FF-lactose adduct was formed in all samples. Interestingly, adduct compounds were also detectable before the storage for stability and stress tests. Incompatibility was confirmed by HPLC-PDA analysis. The mass spectra revealed the m/z of the adduct compound and confirmed the Millard reaction. Browning occurred in the prepared DPI formulations following storage at elevated temperature and humidity. Moreover, adduct compounds were also found in DPI formulations kept at ambient conditions and commercial DPI. Overall, mass spectroscopy was capable of detecting the incompatibility.