Co-milled API-lactose systems for inhalation therapy: impact of magnesium stearate on physico-chemical stability and aerosolization performance

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.

Inhalation Dosage Forms: A Focus on Dry Powder Inhalers and Their Advancements

In this review, an extensive analysis of dry powder inhalers (DPIs) is offered, focusing on their characteristics, formulation, stability, and manufacturing. The advantages of pulmonary delivery were investigated, as well as the significance of the particle size in drug deposition. The preparation of DPI formulations was also comprehensively explored, including physico-chemical characterization of powders, powder processing techniques, and formulation considerations. In addition to manufacturing procedures, testing methods were also discussed, providing insights into the development and evaluation of DPI formulations. This review also explores the design basics and critical attributes specific to DPIs, highlighting the significance of their optimization to achieve an effective inhalation therapy. Additionally, the morphology and stability of 3 DPI capsules (Spiriva, Braltus, and Onbrez) were investigated, offering valuable insights into the properties of these formulations. Altogether, these findings contribute to a deeper understanding of DPIs and their development, performance, and optimization of inhalation dosage forms.

Recent developments in lactose blend formulations for carrier-based dry powder inhalation

Lactose is the most commonly used excipient in carrier-based dry powder inhalation (DPI) formulations. Numerous inhalation therapies have been developed using lactose as a carrier material. Several theories have described the role of carriers in DPI formulations. Although these theories are valuable, each DPI formulation is unique and are not described by any single theory. For each new formulation, a specific development trajectory is required, and the versatility of lactose can be exploited to optimize each formulation. In this review, recent developments in lactose-based DPI formulations are discussed. The effects of varying the material properties of lactose carrier particles, such as particle size, shape, and morphology are reviewed. Owing to the complex interactions between the particles in a formulation, processing adhesive mixtures of lactose with the active ingredient is crucial. Therefore, blending and filling processes for DPI formulations are also reviewed. While the role of ternary agents, such as magnesium stearate, has increased, lactose remains the excipient of choice in carrier-based DPI formulations. Therefore, new developments in lactose-based DPI formulations are crucial in the optimization of inhalable medicine performance.

Advancements in Particle Engineering for Inhalation Delivery of Small Molecules and Biotherapeutics

Dry powder inhalation formulations have become increasingly popular for local and systemic delivery of small molecules and biotherapeutics. Powder formulations provide distinct advantages over liquid formulations such as elimination of cold chain due to room temperature stability, improved portability, and the potential for increasing patient adherence. To become a viable product, it is essential to develop formulations that are stable (physically, chemically and/or biologically) and inhalable over the shelf-life. Physical particulate properties such as particle size, morphology and density, as well as chemical properties can significantly impact aerosol performance of the powder. This review will cover these critical attributes that can be engineered to enhance the dispersibility of inhalation powder formulations. Challenges in particle engineering for biotherapeutics will be assessed, followed by formulation strategies for overcoming the hurdles. Finally, the review will discuss recent examples of successful dry powder biotherapeutic formulations for inhalation delivery that have been clinically assessed.

Optimizing Spray-Dried Porous Particles for High Dose Delivery with a Portable Dry Powder Inhaler

This manuscript critically reviews the design and delivery of spray-dried particles for the achievement of high total lung doses (TLD) with a portable dry powder inhaler. We introduce a new metric termed the product density, which is simply the TLD of a drug divided by the volume of the receptacle it is contained within. The product density is given by the product of three terms: the packing density (the mass of powder divided by the volume of the receptacle), the drug loading (the mass of drug divided by the mass of powder), and the aerosol performance (the TLD divided by the mass of drug). This manuscript discusses strategies for maximizing each of these terms. Spray drying at low drying rates with small amounts of a shell-forming excipient (low Peclet number) leads to the formation of higher density particles with high packing densities. This enables ultrahigh TLD (>100 mg of drug) to be achieved from a single receptacle. The emptying of powder from capsules is directly proportional to the mass of powder in the receptacle, requiring an inhaled volume of about 1 L for fill masses between 40 and 50 mg and up to 3.2 L for a fill mass of 150 mg.

Utilizing Solid-State Techniques and Accelerated Conditions to Understand Particle Size Instability in Inhaled Drug Substances

Micronization by air jet milling is often used to produce drug substance particles of acceptable respirable size for use in dry powder inhaler formulations. The energy from this process often induces surface disordered sites on the micronized particles with potential consequences for the long-term stability of the drug substance. In this study, two lots of the same drug substance were qualitatively determined to have different extents of disordered surface using dynamic vapor sorption and scanning electron microscopy. These differences led to observable divergences in particle size and morphology between lots of drug substances on long-term and accelerated stability. The studies investigate the contribution of temperature and humidity, morphology prior to milling, and stability behavior post-micronization. The results highlight the importance of controlling the crystallization solvents upstream of micronization and their contribution to a material's susceptibility to milling-induced disorder on long-term physical stability. Furthermore, this work proposes an accelerated technique useful in predicting stability behavior of micronized drug substances in days rather than months, especially in cases where small differences cannot be detected by standard solid-state techniques.

Stability and In Vitro Aerodynamic Studies of Inhalation Powders Containing Ciprofloxacin Hydrochloride Applying Different DPI Capsule Types

In the case of capsule-based dry powder inhalation systems (DPIs), the selection of the appropriate capsule is important. The use of gelatin, gelatin-PEG, and HPMC capsules has become widespread in marketed capsule-based DPIs. We aimed to perform a stability test according to the ICH guideline in the above-mentioned three capsule types. The results of the novel combined formulated microcomposite were more favorable than those of the carrier-free formulation for all capsule types. The use of HPMC capsules results in the greatest stability and thus the best in vitro aerodynamic results for both DPI powders after six months. This can be explained by the fact that the residual solvent content (RSC) of the capsules differs. Under the applied conditions the RSC of the HPMC capsule decreased the least and remained within the optimal range, thus becoming less fragmented, which was reflected in the RSC, structure and morphology of the particles, as well as in the in vitro aerodynamic results (there was a difference of approximately 10% in the lung deposition results). During pharmaceutical dosage form developments, emphasis should be placed in the case of DPIs on determining which capsule type will be used for specific formulations.

Development of an Innovative, Carrier-Based Dry Powder Inhalation Formulation Containing Spray-Dried Meloxicam Potassium to Improve the In Vitro and In Silico Aerodynamic Properties

Most of the marketed dry powder inhalation (DPI) products are traditional, carrier-based formulations with low drug concentrations deposited in the lung. However, due to their advantageous properties, their development has become justified. In our present work, we developed an innovative, carrier-based DPI system, which is an interactive physical blend of a surface-modified carrier and a spray-dried drug with suitable shape and size for pulmonary application. Meloxicam potassium, a nonsteroidal anti-inflammatory drug (NSAID), was used as an active ingredient due to its local anti-inflammatory effect and ability to decrease the progression of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). The results of the in vitro and in silico investigations showed high lung deposition in the case of this new formulation, confirming that the interparticle interactions were changed favorably.

Physical stability of dry powder inhaler formulations

Introduction: Dry powder inhalers (DPIs) are popular for pulmonary drug delivery. Various techniques have been employed to produce inhalation drug particles and improve the delivery efficiency of DPI formulations. Physical stability of these DPI formulations is critical to ensure the delivery of a reproducible dose to the airways over the shelf-life.Areas covered: This review focuses on the impact of solid-state stability on aerosolization performance of DPI drug particles manufactured by powder production approaches and particle-engineering techniques. It also highlights the different analytical tools that can be used to characterize the physical instability originating from production and storage.Expert opinion: A majority of the DPI literature focuses on the effects of physico-chemical properties such as size, morphology, and density on aerosolization. While little has been reported on the physical stability, particularly the stability of engineered drug particles for use in DPIs. Literature data have shown that different particle-engineering methods and storage conditions may cause physical instability of dry powders for inhalation and can significantly change the aerosol performance. A systematic examination of physical instability mechanisms in DPI formulations is necessary during formulation development in order to select the optimum formulation with satisfactory stability. In addition, the use of appropriate characterization tools is critical to detect and understand physical instability during the development of DPI formulations.

Correlations between surface composition and aerosolization of jet-milled dry powder inhaler formulations with pharmaceutical lubricants

Co-jet-milling drugs and lubricants may enable simultaneous particle size reduction and surface coating to achieve satisfactory aerosolization performance. This study aims to establish the relationship between surface lubricant coverage and aerosolization behavior of a model drug (ciprofloxacin HCl) co-jet-milled with lubricants [magnesium stearate (MgSt) or l-leucine]. The co-jet-milled formulations were characterized for particle size, morphology, cohesion, Carr's index, and aerosolization performance. The surface lubricant coating was assessed by probing surface chemical composition using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectrometry (ToF-SIMS). The effects of co-jet-milling on the surface energy and in vitro dissolution of ciprofloxacin were also evaluated. Our results indicated that, in general, the ciprofloxacin co-jet-milled with l-leucine at >0.5% w/w showed a significant higher fine particle fraction (FPF) compared with the ciprofloxacin jet-milled alone. The FPF values plateau at or above 5% w/w for both MgSt and l-leucine. We have established the quantitative correlations between surface lubricant coverage and aerosolization in the tested range for each of the lubricants. More importantly, our results suggest different mechanisms to improve aerosolization for MgSt-coating and l-leucine-coating, respectively: MgSt-coating reduces inter-particulate interactions through the formation of low surface energy coating films, while l-leucine-coating not only reduces the surface energy but also creates rough particle surfaces that reduce inter-particulate contact area. Furthermore, surface coatings with 5% w/w MgSt (which is hydrophobic) did not lead to substantial changes in in vitro dissolution. Our findings have shown that the coating structure/quality and their effects could be highly dependent on the process and the coating material. The findings from this mechanistic study provide fundamental understanding of the critical effects of MgSt and l-leucine surface coverages on aerosolization and powder flow properties of inhalation particles.

Stability test of novel combined formulated dry powder inhalation system containing antibiotic: physical characterization and in vitro-in silico lung deposition results

Objective: The aim was to study the stability of dry powder inhaler (DPI) formulations containing antibiotic with different preparation ways - carrier-based, carrier-free, and novel combined formulation - and thereby to compare their physicochemical and in vitro-in silico aerodynamical properties before and after storage. Presenting a novel combined technology in the field of DPI formulation including the carrier-based and carrier-free methods, it is the most important reason to introduce this stable formulation for the further development of DPIs. Methods: The structure, the residual solvent content, the interparticle interactions, the particle size distribution and the morphology of the samples were studied. The aerodynamic values were determined based on the cascade impactor in vitro lung model. We tested the in silico behavior of the novel combined formulated samples before and during storage. Results: The physical measurements showed that the novel combined formulated sample was the most favorable. It was found that thanks to the formulation technique and the use of magnesium stearate (MgSt) has a beneficial effect on the stability compared with the carrier-based formulation without MgSt and carrier-free formulations. The results of in vitro and in silico lung models were consistent with the physical results, so the highest deposition was found for the novel combined formulated sample during the storage. Conclusions: It can be established that after the storage a novel combined formulated DPI contained amorphous drug to have around 2.5 μm mass median aerodynamic diameter and nearly 50% fine particle fraction predicted high lung deposition in silico also.

Simultaneous Particle Size Reduction and Homogeneous Mixing to Produce Combinational Powder Formulations for Inhalation by the Single-Step Co-Jet Milling

Homogeneous mixing of 2 cohesive jet-milled drug powders is a challenge for pharmaceutical manufacturing on account of their cohesive nature resulting in the formation of strong and random agglomerates. In this study, colistin and ciprofloxacin were co-jet milled to develop combinational antibiotic dry powder formulations for inhalation. The properties of particle size, morphology, content uniformity, and in vitro aerosolization were evaluated. The distribution of 2 drugs in the co-jet milled powders was assessed using time-of-flight-secondary ion mass spectrometry. The co-jet milled powders demonstrated an acceptable content uniformity indicating homogeneity. In general, time-of-flight-secondary ion mass spectrometry images showed relatively homogeneous distributions of ciprofloxacin and colistin in the co-milled formulations. Importantly, the 2 drugs generally had the similar fine particle fraction and deposition behavior in each combinational formulation supporting that the particle mixtures were relatively homogenous and could maximize the antimicrobial synergy. In conclusion, co-jet milling could be a viable technique to produce the combination powders for inhalation.

Jet milling industrialization of sticky active pharmaceutical ingredient using quality-by-design approach

Jet milling is frequently used in pharmaceutical industry to achieve different objectives. It can be used as enabling technology to overcome poor water solubility linked to hydrophobic active of pharmaceutical ingredient (API) by reducing the particle size and therefore increasing the dissolution rate. Alternatively, jet milling can be used either to enhance blending efficiency of API with excipient in case of formulation at low dosage strength or to achieve the required particle size for inhalation therapy. In this study, development of commercial manufacturing process of sticky API and its industrialization are described. The methodology used is based on quality-by-design approach to deliver safe, effective and robust manufacturing process. The study showed that the specific energy is a key factor that drives particle size during jet milling and the scale-up from lab to industrial scale. After understanding the process, a design space was built where different zones such as operating point, operating space (where the product is compliant to specification despite variability of process parameters), and the knowledge space were outlined. Finally, an industrial installation was proposed to deliver product with high productivity yield, compliant with safety regulation, and cleanable in place.

Protective effect of sodium stearate on the moisture-induced deterioration of hygroscopic spray-dried powders

Amorphous powders are thermodynamically unstable, significantly impacting the processing, storage and performance of a product. Therefore, stabilization of the amorphous contents is in demand. In this study, disodium cromoglycate (DSCG) powder was chosen as a model drug because it is amorphous and highly hygroscopic after spray drying. Sodium stearate (NaSt) was co-spray dried with DSCG at various concentrations (10, 50 and 90% w/w) to investigate its effect against moisture-induced deterioration on the in vitro aerosolization performance of DSCG. Particle size distribution and morphology were measured by laser diffraction and scanning electron microscopy (SEM). Physicochemical properties of the powders were analysed by X-ray powder diffraction (XRPD) and dynamic vapour sorption (DVS). Particle surface chemistry was analysed by the time-of-flight secondary ion mass spectrometry (ToF-SIMS). In vitro dissolution behaviours of the spray-dried (SD) powders were tested by the Franz cell apparatus. In vitro aerosolization performance of SD formulations stored at different relative humidity (RH) was evaluated by a multi-stage liquid impinger (MSLI), using an Osmohaler® at 100 L/min. Results showed that adding NaSt in the formulation not only increased the aerosolization performance of DSCG significantly, but also effectively reduced the deleterious impact of moisture. No significant difference was found in the fine particle fraction (FPF) of formulations containing NaSt before and after storage at both 60% and 75% RH for one week. However, after one month storage at 75% RH, SD formulation containing 10% NaSt showed a reduction in FPF, while formulations containing 50% or 90% NaSt showed no change. The underlying mechanism was that NaSt increased the crystallinity of the powders and its presence on the particle surface reduced particle aggregations and cohesiveness. However, NaSt at high concentration could reduce dissolution rate, which needs to be taken into consideration.