Dry powder inhaler for pulmonary drug delivery: human respiratory system, approved products and therapeutic equivalence guideline

Pulmonary drug delivery devices and nanosystems as potential treatment strategies for acute respiratory distress syndrome (ARDS)

Despite advances in drug delivery technologies, treating acute respiratory distress syndrome (ARDS) is challenging due to pathophysiological barriers such as lung injury, oedema fluid build-up, and lung inflammation. Active pharmaceutical ingredients (API) can be delivered directly to the lung site of action with the use of aerosol-based drug delivery devices, and this circumvents the hepatic first-pass effect and improves the bioavailability of drugs. This review discusses the various challenges and barriers for pulmonary drug delivery, current interventions for delivery, considerations for effective drug delivery, and the use of nanoparticle drug delivery carriers as potential strategies for delivering therapeutics in ARDS. Nanosystems have the added benefit of entrapping drugs, increase pulmonary drug bioavailability, and using biocompatible and biodegradable excipients that can facilitate targeted and/or controlled delivery. These systems provide an alternative to existing conventional systems. An effective way to deliver drugs for the treatment of ARDS can be by using colloidal systems that are aerosolized or inhaled. Drug distribution to the deeper pulmonary tissues is necessary due to the significant endothelial cell destruction that is prevalent in ARDS. The particle size of nanoparticles (<0.5 μm) makes them ideal candidates for treating ARDS as they can reach the alveoli. A look into the various potential benefits and limitations of nanosystems used for other lung disorders is also considered to indicate how they may be useful for the potential treatment of ARDS.

Repurposing ebselen as an inhalable dry powder to treat respiratory tract infections

Respiratory tract infections (RTIs) are one of the leading causes of death globally, lately exacerbated by the increasing prevalence of antimicrobial resistance. While antimicrobial resistance could be overcome by developing new antimicrobial agents, the use of a safe repurposed agent having potent antimicrobial activity against various RTIs can be an efficient and cost-effective alternative to overcome the long and complex process of developing and testing new drugs. Ebselen, a synthetic organoselenium drug originally developed to treat noise-inducing hearing problems, has shown promising antimicrobial activity in vitro against several respiratory pathogens including viruses (e.g., SARS-CoV-2, influenza A virus) and bacteria (e.g., Mycobacterium tuberculosis, Streptococcus pneumoniae, and Staphylococcus aureus). Inhaled drug delivery is considered a promising approach for treating RTIs, as it can ensure effective drug concentrations at a lower dose, thereby minimizing the side effects that are often encountered by using oral or injectable drugs. In this study, we developed inhalable ebselen dry powder formulations using a spray-drying technique. The amino acids leucine, methionine, and tryptophan were incorporated with ebselen to enhance the yield and aerosolization of the dry powders. The amino acid-containing ebselen dry powders showed a better yield (37-56.4 %) than the amino acid-free formulation (30.9 %). All dry powders were crystalline in nature. The mass median aerodynamic diameter (MMAD) was less than 5 µm for amino acids containing dry powders (3-4 µm) and slightly higher (5.4 µm) for amino acid free dry powder indicating their suitability for inhalation. The aerosol performance was higher when amino acids were used, and the leucine-containing ebselen dry powder showed the highest emitted dose (84 %) and fine particle fraction (68 %). All amino acid formulations had similar cytotoxicity as raw ebselen, tested in respiratory cell line (A549 cells), with half-maximal inhibitory concentrations (IC50) between 100 and 250 μg/mL. Raw ebselen and amino acid-containing dry powders showed similar potent antibacterial activity against the Gram-positive bacteria S. aureus and S. pneumoniae with minimum inhibitory concentrations of 0.31 μg/mL and 0.16 μg/mL, respectively. On the other hand, raw ebselen and the formulations showed limited antimicrobial activity against the Gram-negative pathogens Pseudomonas aeruginosa and Klebsiella pneumoniae. In summary, in this study we were able to develop amino-acid-containing inhalable dry powders of ebselen that could be used against different respiratory pathogens, especially Gram-positive bacteria, which could ensure more drug deposition in the respiratory tract, including the lungs. DPIs are generally used to treat lung (lower respiratory tract) diseases. However, DPIs can also be used to treat both upper and lower RTIs. The deposition of the dry powder in the respiratory tract is dependent on its physicochemical properties and this properties can be modulated to target the intended site of infection (upper and/or lower respiratory tract). Further studies will allow the development of similar formulations of individual and/or combination of antimicrobials that could be used to inhibit a number of respiratory pathogens.

Supercritical antisolvent-fluidized bed for the preparation of dry powder inhaler for pulmonary delivery of nanomedicine

The supercritical antisolvent-fluidized bed coating process (SAS-FB) shows great potential as a technique to manufacture dry powder inhaler (DPI) that incorporate nanodrugs onto micronized matrix particles, capitalizing on the merits of both nanoparticle and pulmonary delivery. In this study, naringin (NAR), a pharmacologically active flavonoid with low solubility and in vivo degradation issues, was utilized as a model active pharmaceutical ingredient to construct nanomedicine-based DPI through SAS-FB. It is showed that processed NAR exhibited a near-spherical shape and an amorphous structure with an average size of around 130 nm. Notably, SAS-FB products prepared with different fluidized matrices resulted in varying deposition patterns, particularly when mixed with a coarse lactose to enhance the fine particle fraction (FPF) of the formulations. The FPF was positively associated with specific surface area of the SAS-FB products, while the specific surface area was directly related to surface roughness and particle size. In vitro dissolution studies using simulated lung fluid revealed that the NAR nanoparticles coated on the products were released immediately upon contact with solution, with a cumulative dissolution exceeding 90% within the first minute. Importantly, compared to oral raw NAR, the optimized DPI formulation demonstrated superior in vivo plasmatic and pulmonary AUC0→∞ by 51.33-fold and 104.07-fold respectively in a Sprague-Dawley rat model. Overall, SAS- FB technology provides a practical approach to produce nanomedicine DPI product that combine the benefits of nanoparticles with the aerodynamics properties of inhaled microparticles.

Inhalable dry powder containing remdesivir and disulfiram: Preparation and in vitro characterization

The respiratory tract, as the first and most afflicted target of many viruses such as SARS-CoV-2, seems to be the logical choice for delivering antiviral agents against this and other respiratory viruses. A combination of remdesivir and disulfiram, targeting two different steps in the viral replication cycle, has showed synergistic activity against SARS-CoV-2 in-vitro. In this study, we have developed an inhalable dry powder containing a combination of remdesivir and disulfiram utilizing the spray-drying technique, with the final goal of delivering this drug combination to the respiratory tract. The prepared dry powders were spherical, and crystalline. The particle size was between 1 and 5 μm indicating their suitability for inhalation. The spray-dried combinational dry powder containing remdesivir and disulfiram (RDSD) showed a higher emitted dose (ED) of >88% than single dry powder of remdesivir (RSD) (∼72%) and disulfiram (DSD) (∼84%), with a fine particle fraction (FPF) of ∼55%. Addition of L-leucine to RDSD showed >60% FPF with a similar ED. The in vitro aerosolization was not significantly affected after the stability study conducted at different humidity conditions. Interestingly, the single (RSD and DSD) and combined (RDSD) spray-dried powders showed limited cellular toxicity (CC50 values from 39.4 to >100 µM), while maintaining their anti-SARS-CoV-2 in vitro (EC50 values from 4.43 to 6.63 µM). In a summary, a combinational dry powder formulation containing remdesivir and disulfiram suitable for inhalation was developed by spray-drying technique which showed high cell viability in the respiratory cell line (Calu-3 cells) retaining their anti-SARS-CoV-2 property. In the future, in vivo studies will test the ability of these formulations to inhibit SARS-CoV-2 which is essential for clinical translation.

Effect of laryngeal jet on dry powder inhaler aerosol deposition: a numerical simulation

Although pulmonary drug delivery has been deeply investigated, the effect of the laryngeal jet on particle deposition during drug delivery with dry powder inhalers (DPI) has not been evaluated profoundly. In this study, the flow structure and particle deposition pattern of a DPI in two airway models, one with mouth-throat region including the larynx and the other one without it, are numerically investigated. The results revealed that the laryngeal jet has a considerable effect on particle deposition. The presence of laryngeal jet leads to 4-fold and 2-fold higher deposition efficiencies for inlet flow rates of 30 and 90 L/min, respectively.

Spray-Dried Inhalable Microparticles Combining Remdesivir and Ebselen against SARS-CoV-2 Infection

There is a continuous effort to develop efficient treatments for coronavirus disease 2019 (COVID-19) and other viral respiratory diseases. Among the different strategies, inhaled treatment is considered one of the most logical and efficient approaches to treating COVID-19, as the causative "SARS-CoV-2 virus RNA" predominantly infects the respiratory tract. COVID-19 treatments initially relied on repurposed drugs, with a few additional strategies developed during the last two years, and all of them are based on monotherapy. However, drug combinations have been found to be more effective than monotherapy in other viral diseases such as HIV, influenza, and hepatitis C virus. In the case of SARS-CoV-2 infection, in vitro studies have shown synergistic antiviral activity combining remdesivir with ebselen, an organoselenium compound. Therefore, these drug combinations could ensure better therapeutic outcomes than the individual agents. In this study, we developed a dry powder formulation containing remdesivir and ebselen using a spray-drying technique and used L-leucine as an aerosolization enhancer. The prepared dry powders were spherical and crystalline, with a mean particle size between 1 and 3 µm, indicating their suitability for inhalation. The emitted dose (ED) and fine particle fraction (FPF) of remdesivir- and ebselen-containing dry powders were ~80% and ~57% when prepared without L-leucine. The ED as well as the FPF significantly increased with values of >86% and >67%, respectively, when L-leucine was incorporated. More importantly, the single and combinational dry powder of remdesivir and ebselen showed minimal cytotoxicity (CC50 > 100 μM) in Calu-3 cells, retaining their anti-SARS-CoV-2 properties (EC50 2.77 to 18.64 μM). In summary, we developed an inhalable dry powder combination of remdesivir and ebselen using a spray-drying technique. The spray-dried inhalable microparticles retained their limited cytotoxicity and specific antiviral properties. Future in vivo studies are needed to verify the potential use of these remdesivir/ebselen combinational spray-dried inhalable microparticles to block the SARS-CoV-2 replication in the respiratory tract.

Role of dispersion enhancer selection in the development of novel tratinterol hydrochloride dry powder inhalation formulations

Tratinterol hydrochloride (TH) is a new long-acting bronchodilator with strong β₂ adrenoceptor stimulation activity. The aim of this study was to design a new carrier-based dry powder inhalation (DPI) formulation for TH and to investigate the effect of dispersion enhancers on the aerosol performance of TH in vitro. To this end, coarse lactose was used as a carrier. TH was micronized by using a jet mill and blended with the carrier to obtain a reference DPI formulation. Commercial magnesium stearate (MgSt) as received, micronized MgSt (MgSt-M), and fine lactose (FL) were used as the dispersion enhancers and formulated with the micronized TH (TH-M) and the carrier as DPI formulations. The obtained DPI formulations were characterized using dynamic light scattering (DLS), X-ray powder diffraction (XRPD), thermal analysis, powder rheometer, and Raman microscopy. A next generation pharmaceutical impactor (NGI) was used to evaluate the aerodynamic performance of the dry powders. The results showed that TH-M was in an inhalable particle size range, and based on the XRPD and thermal analysis, the solid form of TH-M did not change compared to the starting materials. The NGI results showed that the fine particle fraction (FPF) of TH could be increased with the addition of MgSt and FL as dispersion enhancers in the reference formulation. In addition, the FPF of TH could be increased with a decrease in the particle size of MgSt or an increase in the amount of FL. A combination of MgSt-M and FL could further improve the aerosol performance of TH. Raman spectroscopic imaging confirmed the spatial location of MgSt and TH at the surface of the carrier. This study demonstrates that TH could be formulated into carrier-based dry powder formulation for inhalation using coarse lactose as the carrier. The dual strategy based on using both MgSt and FL as dispersion enhancers improved the aerosol performance of a novel TH dry powder formulation.

Antiviral peptides against SARS-CoV-2: therapeutic targets, mechanistic antiviral activity, and efficient delivery

The global pandemic of COVID-19 is a serious public health concern. Over 625 million confirmed cases and more than 6 million deaths have been recorded worldwide. Although several vaccines and antiviral medications have been developed, their efficacy is limited by the emerging new SARS-CoV-2 strains. Peptide-based therapeutics is a fast-growing class of new drugs and have unique advantages over large proteins and small molecules. Antiviral peptides (AVPs) are short polycationic antivirals with broad-spectrum effects, which have been shown to exert both prophylactic and therapeutic actions against reported coronaviruses. The potential therapeutic targets of AVPs are located either on the virus (e.g., E-protein and S-protein) to prohibit viral binding or host cells, particularly, those present on the cell surface (e.g., ACE2 and TMPRSS2). Despite AVPs having promising antiviral effects, their efficacy is limited by low bioavailability. Thus, nanoformulation is a prerequisite for prolonged bioavailability and efficient delivery. This review aimed to present an insight into the therapeutic AVP targets on both virus and host cells by discussing their antiviral activities and associated molecular mechanisms. Besides, it described the technique for discovering and developing possible AVPs based on their targets, as well as the significance of using nanotechnology for their efficient delivery against SARS-CoV-2.

Inhalable Nano-Dimpled Microspheres Containing Budesonide-PLGA for Improved Aerodynamic Performance

Introduction

Dry powder inhalations are an attractive pharmaceutical dosage form. They are environmentally friendly, portable, and physicochemical stable compared to other inhalation forms like pressurized metered-dose inhalers and nebulizers. Sufficient drug deposition of DPIs into the deep lung is required to enhance the therapeutic activity. Nanoscale surface roughness in microparticles could improve aerosolization and aerodynamic performance. This study aimed to prepare microspheres with nanoscale dimples and confirm the effect of roughness on inhalation efficiency.

Methods

The dimpled-surface on microspheres (MSs) was achieved by oil in water (O/W) emulsion-solvent evaporation by controlling the stirring rate. The physicochemical properties of MSs were characterized. Also, in vitro aerodynamic performance of MSs was evaluated by particle image velocimetry and computational fluid dynamics.

Results

The particle image velocimetry results showed that dimpled-surface MSs had better aerosolization, about 20% decreased X-axial velocity, and a variable angle, which could improve the aerodynamic performance. Furthermore, it was confirmed that the dimpled surface of MSs could cause movement away from the bronchial surface, which helps the MSs travel into the deep lung using computational fluid dynamics.

Conclusion

The dimpled-surface MSs showed a higher fine particle fraction value compared to smooth-surface MSs in the Andersen Cascade Impactor, and surface roughness like dimples on microspheres could improve aerosolization and lung deposition.

Inhaled therapy for COVID-19: Considerations of drugs, formulations and devices

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent responsible for the COVID-19 pandemic, has outspread at full tilt across the world. Although several effective vaccines continue to be deployed, reliable antiviral treatments have yet to be developed against this disease. Currently, available therapeutics for COVID-19 include repurposed, and a few novel drugs. Many drugs have been promising in preclinical studies, but a majority of these drugs have shown little or no efficacy in clinical studies. One of the major reasons is the insufficient drug concentration in the lung, the primary target site of infection for SARS-CoV-2, from the administration of drugs through oral or intravenous routes. Higher effective doses administered through these routes could also lead to adverse side effects. For this reason, inhaled treatments are being tested as an efficient approach for COVID-19, allowing lower doses of drugs ensuring higher concentrations of the drug(s) in the lung. The inhaled treatment combining two or more antiviral drugs will increase potency and reduce the possibility of selecting for SARS-CoV-2 variants with reduced drug susceptibility. Finally, the appropriate drug combination needs to be delivered using a suitable system. Here, we review the current treatment for COVID-19 and their limitations, discussing the advantages of mono and combinational inhaled therapy with a brief outline of the recently reformulated anti-SARS-CoV-2 agents as inhaled formulations. The selection of appropriate delivery devices for inhalation and associated key considerations including the formulation challenges are also discussed.

The future of dry powder inhaled therapy: Promising or Discouraging for systemic disorders?

Dry powder inhalation therapy has been shown to be an effective method for treating respiratory diseases like asthma, Chronic Obstructive Pulmonary Diseases and Cystic Fibrosis. It has also been widely accepted and used in clinical practices. Such success has led to great interest in inhaled therapy on treating systemic diseases in the past two decades. The current coronavirus (COVID-19) pandemic also has increased such interest and is triggering more potential applications of dry powder inhalation therapy in vaccines and antivirus drugs. Would the inhaled dry powder therapy on systemic disorders be as encouraging as expected? This paper reviews the marketed and in-development dry powder inhaler (DPI) products on the treatment of systemic diseases, their status in clinical trials, as well as the potential for COVID-19 treatment. The advancements and unmet problems on DPI systems are also summarized. With countless attempts behind and more challenges ahead, it is believed that the dry powder inhaled therapy for the treatment of systemic disorders still holds great potential and promise.

Albumin grafted coaxial electrosparyed polycaprolactone-zinc oxide nanoparticle for sustained release and activity enhanced antibacterial drug delivery

One of the most serious issues faced by the healthcare sector is the development of multidrug resistance among various pathogens. It is such that developing new and more capable drugs takes far too long to counter such resistance. In order to overcome these concerns, this study focused on improving upon the coaxial electrospraying process by producing cloxacillin loaded albumin polycaprolactone (PCL) with a ZnO coating for sustained and activity enhanced drug delivery. Albumin-grafted, polycaprolactone-coated, zinc oxide-loaded cloxacillin (APCL-CLOX-ZnO) nanoparticles with a diameter of 85-110 nm were obtained via a coaxial electrospray technique. The encapsulation efficiency of cloxacillin of ZnO-CLOX was found to be approximately 60%. The loading efficiencies of ZnO-CLOX and APCL-CLOX-ZnO were found to be 40% and 28% respectively. Albumin was employed in order to impart immune evasion properties to the formulation. Drug-loaded ZnO NPs were analyzed using SEM, TEM, FT-IR and TGA. This novel formulation was shown to possess sustained release characteristics owing to the PCL and albumin coatings, relative to uncoated counterparts. ZnO-CLOX and APCL-CLOX-ZnO exhibited 72% and 52% cloxacillin release within 24 h. APCL-CLOX-ZnO exhibited potent antimicrobial activity against S. epidermidis, B. cereus and P. aeruginosa and some activity against E. coli with inhibition zones 32 ± 1.4, 34 ± 0.3, 32 ± 0.6 and 11 ± 0.4 mm, respectively. Cytotoxicity studies against murine preosteoblast cells revealed that the albumin-PCL coating served to drastically reduce initial toxicity against healthy mammalian cells. In vitro lung deposition study showed 70% of APCL-CLOX-ZnO particles can reach up to the alveoli level. Therefore, this novel coaxial nanoformulation may serve as a promising drug delivery platform for the treatment of bacterial infections including respiratory tract complications.

Co-Amorphization of Kanamycin with Amino Acids Improves Aerosolization

Different formulation techniques have been investigated to prepare highly aerosolizable dry powders to deliver a high dose of antibiotics to the lung for treating local infections. In this study, we investigated the influence of the co-amorphization of a model drug, kanamycin, with selected amino acids (valine, methionine, phenylalanine, and tryptophan) by co-spray drying on its aerosolization. The co-amorphicity was confirmed by thermal technique. The physical stability was monitored using low-frequency Raman spectroscopy coupled with principal component analysis. Except for the kanamycin-valine formulation, all the formulations offered improved fine particle fraction (FPF) with the highest FPF of 84% achieved for the kanamycin-methionine formulation. All the co-amorphous formulations were physically stable for 28 days at low relative humidity (25 °C/<15% RH) and exhibited stable aerosolization. At higher RH (53%), even though methionine transformed into its crystalline counterpart, the kanamycin-methionine formulation offered the best aerosolization stability without any decrease in FPF. While further studies are warranted to reveal the underlying mechanism, this study reports that the co-amorphization of kanamycin with amino acids, especially with methionine, has the potential to be developed as a high dose kanamycin dry powder formulation.

Novel approach for real-time monitoring of carrier-based DPIs delivery process via pulmonary route based on modular modified Sympatec HELOS

An explicit illustration of pulmonary delivery processes (PDPs) was a prerequisite for the formulation design and optimization of carrier-based DPIs. However, the current evaluation approaches for DPIs could not provide precise investigation of each PDP separately, or the approaches merely used a simplified and idealized model. In the present study, a novel modular modified Sympatec HELOS (MMSH) was developed to fully investigate the mechanism of each PDP separately in real-time. An inhaler device, artificial throat and pre-separator were separately integrated with a Sympatec HELOS. The dispersion and fluidization, transportation, detachment and deposition processes of pulmonary delivery for model DPIs were explored under different flow rates. Moreover, time-sliced measurements were used to monitor the PDPs in real-time. The Next Generation Impactor (NGI) was applied to determine the aerosolization performance of the model DPIs. The release profiles of the drug particles, drug aggregations and carriers were obtained by MMSH in real-time. Each PDP of the DPIs was analyzed in detail. Moreover, a positive correlation was established between the total release amount of drug particles and the fine particle fraction (FPF) values (R ² = 0.9898). The innovative MMSH was successfully developed and was capable of illustrating the PDPs and the mechanism of carrier-based DPIs, providing a theoretical basis for the design and optimization of carrier-based DPIs.