Impact of human behavior on inspiratory flow profiles in patients with pulmonary arterial hypertension using AOS™ dry powder inhaler device

Design of dry powder inhalers to improve patient outcomes: it's not just about the device

INTRODUCTION

Up to 50% of asthma/COPD patients make critical errors in dose preparation and dose inhalation with current marketed DPIs which negatively impact clinical outcomes. Others fail to adhere to their chronic treatment regimen.

AREAS COVERED

For this review, we describe how a human-factors approach to design of a dry powder inhaler can be used to improve usability, proficiency, and functionality of DPIs, while effectively mitigating critical errors associated with DPIs. The review highlights the critical importance of utilizing improved formulations with monomodal aerodynamic particle size distributions to reduce variability associated with oropharyngeal filtering of particles, flow rate dependence, and co-formulation effects.

EXPERT OPINION

Much of the variability in dose delivery with DPIs is associated with limitations of the bimodal APSDs inherent in current lactose blend formulations. Evidence supports that improved lung targeting and dose consistency can be achieved with drug-device combination products comprising spray-dried powders. Unfortunately, no data exists to assess whether these advances observed in in vitro and in vivo dose delivery studies will translate into improved clinical outcomes. Given the significant percentage of patients that receive suboptimal drug delivery with current DPIs it would behoove the industry to assess the efficacy of new approaches.

The nitric oxide-soluble guanylate cyclase-cGMP pathway in pulmonary hypertension: from PDE5 to soluble guanylate cyclase

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway plays a key role in the pathogenesis of pulmonary hypertension (PH). Targeted treatments include phosphodiesterase type 5 inhibitors (PDE5i) and sGC stimulators. The sGC stimulator riociguat is approved for the treatment of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). sGC stimulators have a dual mechanism of action, enhancing the sGC response to endogenous NO and directly stimulating sGC, independent of NO. This increase in cGMP production via a dual mechanism differs from PDE5i, which protects cGMP from degradation by PDE5, rather than increasing its production. sGC stimulators may therefore have the potential to increase cGMP levels under conditions of NO depletion that could limit the effectiveness of PDE5i. Such differences in mode of action between sGC stimulators and PDE5i could lead to differences in treatment efficacy between the classes. In addition to vascular effects, sGC stimulators have the potential to reduce inflammation, angiogenesis, fibrosis and right ventricular hypertrophy and remodelling. In this review we describe the evolution of treatments targeting the NO-sGC-cGMP pathway, with a focus on PH.

Tyvaso DPI: Drug-device characteristics and patient clinical considerations

Tyvaso DPI is a drug-device combination therapy comprised of a small, portable, reusable, breath-powered, dry powder inhaler (DPI) for the delivery of treprostinil. It is approved for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. Tyvaso DPI utilizes single-use prefilled cartridges to ensure proper dosing. Unlike nebulizer devices, administration of Tyvaso DPI is passive and does not require coordination with the device. The low-flow rate design results in targeted delivery to the peripheral lungs due to minimal drug loss from impaction in the oropharynx. The inert fumaryl diketopiperazine (FDKP) excipient forms microparticles that carry treprostinil into the airways, with a high fraction of the particles in the respirable range. In a clinical study in patients with pulmonary arterial hypertension, Tyvaso DPI had similar exposure and pharmacokinetics, low incidence of adverse events, and high patient satisfaction compared with nebulized treprostinil solution. Tyvaso DPI may be considered as a first prostacyclin agent or for those that do not tolerate other prostacyclin formulations, patients with pulmonary comorbidities, patients with mixed Group 1 and Group 3 pulmonary hypertension, or those that prefer an active lifestyle and need a portable, non-invasive treatment. Tyvaso DPI is a patient-preferred, maintenance-free, safe delivery option that may improve patient compliance and adherence.

High inhaler resistance does not limit successful inspiratory maneuver among patients with asthma or COPD

INTRODUCTION

There has been an active discussion on the sustainability of inhaler therapy in respiratory diseases, and it has cast a shadow on pMDIs which rely on propellant with high global warming potential (GWP). DPIs offer a lower GWP and effective alternative, but there has been concern whether all patients can generate sufficient inspiratory effort to disperse the drug. This review focuses on airflow resistance of DPIs and its clinical relevance.

AREAS COVERED

For this narrative review, we searched the literature for studies comparing flow patterns with different devices. We also included a section on clinical trials comparing reliever administration with DPI, pMDI with spacer, and nebulizer during exacerbation.

EXPERT OPINION

The evidence supports the efficacy of DPIs irrespective of respiratory condition or age of the patient even during acute exacerbations. Air flow resistance does not limit the use of DPIs and the patients were able to generate sufficient inspiratory flow rate with almost any device studied. None of 16 identified clinical trials comparing reliever administration via DPIs to other types of devices during exacerbation or bronchial challenge showed statistically significant difference between the device types in FEV1 recovery. DPIs performed as well as other types of inhaler devices even during asthma or COPD exacerbation.

The evolving landscape of pulmonary arterial hypertension clinical trials

Although it is a rare disease, the number of available therapeutic options for treating pulmonary arterial hypertension has increased since the late 1990s, with multiple drugs developed that are shown to be effective in phase 3 randomised controlled trials. Despite considerable advancements in pulmonary arterial hypertension treatment, prognosis remains poor. Existing therapies target pulmonary endothelial dysfunction with vasodilation and anti-proliferative effects. Novel therapies that target proliferative vascular remodelling and affect important outcomes are urgently needed. There is need for additional innovations in clinical trial design so that all emerging candidate therapies can be rigorously studied. Pulmonary arterial hypertension trial design has shifted from short-term submaximal exercise capacity as a primary endpoint, to larger clinical event-driven trial outcomes. Event-driven pulmonary arterial hypertension trials could face feasibility and efficiency issues in the future because increasing sample sizes and longer follow-up durations are needed, which would be problematic in such a rare disease. Enrichment strategies, innovative and alternative trial designs, and novel trial endpoints are potential solutions that could improve the efficiency of future pulmonary arterial hypertension trials while maintaining robustness and clinically meaningful evidence.

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.

Targeting of Inhaled Therapeutics to the Small Airways: Nanoleucine Carrier Formulations

Current dry powder formulations for inhalation deposit a large fraction of their emitted dose in the upper respiratory tract where they contribute to off-target adverse effects and variability in lung delivery. The purpose of the current study is to design a new formulation concept that more effectively targets inhaled dry powders to the large and small airways. The formulations are based on adhesive mixtures of drug nanoparticles and nanoleucine carrier particles prepared by spray drying of a co-suspension of leucine and drug particles from a nonsolvent. The physicochemical and aerosol properties of the resulting formulations are presented. The formulations achieve 93% lung delivery in the Alberta Idealized Throat model that is independent of inspiratory flow rate and relative humidity. Largely eliminating URT deposition with a particle size larger than solution pMDIs is expected to improve delivery to the large and small airways, while minimizing alveolar deposition and particle exhalation.

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.