Canister valve and actuator deposition in metered dose inhalers formulated with low-GWP propellants.

A challenge in pressurised metered-dose inhaler (pMDI) formulation design is management of adhesion of the drug to the canister wall, valve and actuator internal components and surfaces. Wall-material interactions differ between transparent vials used for visual inspection and metal canister pMDI systems. This is of particular concern for low greenhouse warming potential (GWP) formulations where propellant chemistry and solubility with many drugs are not well understood. In this study, we demonstrate a novel application of X-ray fluorescence spectroscopy using synchrotron radiation to assay the contents of surrogate solution and suspension pMDI formulations of potassium iodide and barium sulphate in propellants HFA134a, HFA152a and HFO1234ze(E) using aluminium canisters and standard components. Preliminary results indicate that through unit life drug distribution in the canister valve closure region and actuator can vary significantly with new propellants. For solution formulations HFO1234ze(E) propellant shows the greatest increase in local deposition inside the canister valve closure region as compared to HFA134a and HFA152a, with correspondingly reduced actuator deposition. This is likely driven by chemistry changes. For suspension formulations HFA152a shows the greatest differences, due to its low specific gravity. These changes must be taken into consideration in the development of products utilising low-GWP propellants.

Metered dose inhalers in the transition to low GWP propellants: what we know and what is missing to make it happen.

INTRODUCTION: The urgency to replace the propellants currently in use with the new sustainable ones has given rise to the need for investigation and reformulation of pMDIs. AREAS COVERED: The reformulation requires in-depth knowledge of the physico-chemical characteristics of the new propellants, which impact the atomization capacity and the plume geometry. Among the investigated propellants, HFA 152a, due to its lower vapor pressure and higher surface tension compared to HFA 134a, deliver larger particles and has a higher solvent capacity toward lipophilic drugs. On the other hand, HFO 1234ze has properties more similar to HFA 134a, but showed lower reproducibility of the generated spray, indicating a possible high susceptibility to variation in the consistency of the dose delivered. In addition, the device components currently in use are compatible with the new propellants. This allowed promising preliminary results in the re-formulation of pMDIs by academia and pharma companies. However, there is little information about the clinical studies required to allow the marketing of these new products. EXPERT OPINION: Overall, studies conducted so far show that the transition is technically possible, and the main obstacle will be represented by the investment required to put the product on the market.

HS-GC-FID method for quantification of HFA-152a in cell culture media, and plasma from a range of species and regulatory compliant validations.

INTRODUCTION: 1,1-Difluoroethane (HFA-152a) is being developed as an alternative propellant in pressurized metered dose inhalers (pMDIs). As a part of the regulatory development pathway, pharmacology, toxicology and clinical studies have been conducted with inhaled HFA-152a. These studies require fit for purpose regulatory compliant (GxP validated) methods for quantification of HFA-152a from blood. METHODS: As HFA-152a is a gas at standard temperature and pressure, novel methods were developed to support the analysis across the wide range of species and concentrations required for regulatory filing. RESULTS: The developed methods utilized a headspace auto sampler coupled to a gas chromatograph (GC) with flame ionization detection. Key factors in the successful method included bringing together fit for purpose approaches to the head space vials, volume of matrix (blood), detection range required for species/study objective, handling / transfer of blood into head space vials and the stability/storage required for the analysis of the samples. The species-specific assays were fully validated under regulatory (GLP) conditions for mouse, rat, rabbit, canine and human and non-regulatory (non GLP) validations for guinea pig and cell culture media. DISCUSSION: Overall the novel approach of head space analysis of whole blood allowed for the development and validation of assays used to generate the toxicokinetic data that supported clinical testing of HFA-152a as a new pMDI propellant.

Transport and deposition of beclomethasone dipropionate drug aerosols with varying ethanol concentration in severe asthmatic subjects.

This study aims to assess the effects of varying an ethanol co-solvent on the deposition of drug particles in severe asthmatic subjects with distinct airway structures and lung functions using computational fluid dynamics. The subjects were selected from two quantitative computed tomography imaging-based severe asthmatic clusters, differentiated by airway constriction in the left lower lobe. Drug aerosols were assumed to be generated from a pressurized metered-dose inhaler (MDI). The aerosolized droplet sizes were varied by increasing the ethanol co-solvent concentration in the MDI solution. The MDI formulation consists of 1,1,2,2-tetrafluoroethane (HFA-134a), ethanol, and beclomethasone dipropionate (BDP) as the active pharmaceutical ingredient. Since HFA-134a and ethanol are volatile, both substances evaporate rapidly under ambient conditions and trigger condensation of water vapor, increasing the size of aerosols that are predominantly composed of water and BDP. The average deposition fraction in intra-thoracic airways for severe asthmatic subjects with (or without) airway constriction increased from 37%±12 to 53.2%±9.4 (or from 20.7%± 4.6 to 34.7%±6.6) when the ethanol concentration was increased from 1 to 10%wt/wt. However, when the ethanol concentration was further increased from 10 to 20%wt/wt, the deposition fraction decreased. This indicates the importance of selecting appropriate co-solvent amounts during drug formulation development for the treatment of patients with narrowed airway disease. For severe asthmatic subjects with airway narrowing, the inhaled aerosol may benefit from a low hygroscopic effect by reducing ethanol concentration to penetrate the peripheral region effectively. These results could potentially inform the selection of co-solvent amounts for inhalation therapies in a cluster-specific manner.

How to engineer aerosol particle properties and biopharmaceutical performance of propellant inhalers.

Given the environmental compulsion to reformulate pressurised metered dose inhalers (pMDI) using new propellants with lower global warming potential, this study investigated how non-volatile excipients can be used to engineer aerosol particle microphysics and drug release. The dynamics of change in particle size, wetting and physical state were measured for single particles (glycerol/ethanol/beclomethasone dipropionate; BDP) in the aerosol phase at different relative humidity (RH) using an electrodynamic balance. BDP dissolution rates were compared for aerosols from pMDI containing different ratios of BDP:glycerol or BDP:isopropyl myristate (IPM). In 45 % RH, ethanol loss was followed by evaporation of condensed water to generate spherical particles with solid inclusions or compact irregular-shaped solid particles, according to the presence or absence of glycerol. In RH > 95 %, condensed water did not evaporate and BDP formed solid inclusions in water/glycerol or water droplets. Varying the non-volatile component, 0-50 % w/w, in pMDI resulted in a concentration-dependent 4-8-fold reduction in BDP dissolution rate. These findings demonstrate that non-volatile excipients provide a means of engineering aerosol properties and, modifying the rate of drug release from aerosol medicines. We also demonstrated differences between particles formed in vitro in ambient humidity versus higher humidity, more like that encountered during oral inhalation.

Detection of Asthma Inhaler Use via Terahertz Spectroscopy.

Inhaled medications are commonplace for administering bronchodilators, anticholinergics, and corticosteroids. While they have a defined legitimate use, they are also used in sporting events as performance-enhancing drugs. These performance enhancers can be acquired via both legal (i.e., at a pharmacy through over-the-counter medications or through a prescription) and illicit (i.e., black market and foreign pharmacies) means, thus making monitoring procurement impossible. While urine tests can detect these pharmacological agents hours after they have been inhaled, there is a significant lag time before they are observed in urine. Direct detection of these inhaled agents is complicated and requires a multiplexed approach due to the sheer number of inhaled pharmacological agents. Therefore, detection of propellants, which carry the drug into the lungs, provides a simpler path forward toward detection of broad pharmacological agents. In this paper, we demonstrate the first use of terahertz spectroscopy (THz) to detect inhaled medications in human subjects. Notably, we were able to detect and quantitate the propellant, HFA-134a, in breath up to 30 min after using an asthma inhaler, enabling the use of a point-of-care device to monitor exhaled breath for the presence of propellants. We also demonstrate via simulations that the same approach can be leveraged to detect and identify next-generation propellants, specifically HFA-152a. As a result, we provide evidence that a single point-of-care THz sensor can detect when individuals have used pressure-mediated dose inhalers (pMDIs) without further modification of the hardware.

Acute, repeated inhalation toxicity, respiratory system irritation, and mutagenicity studies of 1,1,2,2-tetrafluoroethane (HFC-134) as the impurity in the pharmaceutical propellant 1,1,1,2-tetrafluoroethane (HFA-134a).

HFC-134 is the main impurity of HFA-134a. In order to verify the rationality of HFC-134 limits in HFA-134a and ensure the safety of HFA-134a as propellant in pharmaceutical metered-dose inhalers, acute inhalation toxicity, seven-day repeat dose inhalation irritation study, 21-day repeat dose inhalation toxicity study and reverse mutation assay of HFC-134 were tested to evaluate its inhalation safety. In acute inhalation studies, Sprague-Dawley rats were exposed nose-only to HFC-134 at levels of 100 000, 200 000, 400 000, 600 000, and 800 000 ppm for 4 h. Based on the mortality incidence, the calculated four-hour LC50 value for HFC-134 is 532 069 ppm for males and 502 058 ppm for females and acute inhalation toxicity is manifested as the lung lobes turn dark red. Exposures to 836 ± 67 ppm for 4 hours/day 7 days/week continuously did not induce local irritation of the respiratory system in Sprague-Dawley rats. Sprague-Dawley rats were exposed nose-only to HFC-134 at levels of 0 (control), 203 929 ppm and 394 871 ppm 2 h/day for 21 consecutive days, no significant treatment-related adverse effects was noted. Results from Ames studies demonstrated that HFC-134 was not mutagenic. Although HFC-134 has a very low acute inhalation toxicity, considering that its acute inhalation toxicity is higher than that of HFA-134a, and due to the high frequency of use of MDI by asthma patients, acceptance criteria of HFC-134 as the impurity in aerosol propellant HFA-134a should be lower than 8-h TWA WEEL value of 1000 ppm to ensure the safety of the MDI.

Iatrogenic cold urticaria induced by tetrafluoroethane cryosurgery for gingival depigmentation: A rare case report.

INTRODUCTION: Gingival depigmentation procedure has gained widespread popularity in the recent years due to increased esthetic demands among patients. Among the various depigmentation procedures, cryosurgery is inexpensive and straightforward method. This case report discusses a rare complication associated with tetrafluoroethane (TFE) cryosurgical depigmentation method. CASE PRESENTATION: A 27-year-old systemically healthy male patient reported with the complaint of esthetic concerns associated with gingival melanin pigmentation. Cryosurgery with TFE was planned for the maxillary first quadrant. The patient developed angioedema immediately after exposure to the TFE cryogen during the procedure. Cold urticaria was considered, and the patient was prescribed nonsedating antihistamines for a week. One month follow-up showed completely healed and depigmented gingiva without any recession or attachment loss. CONCLUSIONS: TFE cryosurgery depigmentation was found to be an effective depigmentation procedure. However, various complications including cold urticaria have been associated with its application. Therefore, the procedure's success depends on the proper case selection, complete isolation of the operating area, and preoperative test for gingival tissue response. KEY POINTS: Why is this case new information? Cold urticaria formation after applying cryosurgery has never been reported in the literature to the best of the authors' knowledge. What are the keys to the successful management of this case? Preoperative testing for tissue response to cryosurgery will prevent complications like cold urticaria. What are the primary limitations to success in this case? Improper medical history and not taking tissue response test for cryosurgery.

Case 298: Skeletal Fluorosis Secondary to Huffing.

History A 37-year-old man from the United States presented with a 1-year history of neck pain and stiffness that had been unsuccessfully treated with manipulative therapy by a chiropractor at another institution. Past medical history was remarkable only for marijuana and air duster abuse. He denied use of any prescription medications. Physical examination was notable for markedly reduced range of motion of the cervical spine. Laboratory work-up revealed an elevated alkaline phosphatase level (302 U/L [5.0 µkat/L]; normal range, 40-100 U/L [0.7-1.67 µkat/L]), but all other laboratory findings, including complete blood count, renal function, liver function, vitamin A level, serum protein electrophoresis, and hepatitis C antibodies were within normal limits. Cervical spine radiography was performed, followed by MRI. Subsequently, a full skeletal survey was ordered. Included are representative radiographs of the pelvis, left forearm, and distal right leg with ankle.

Droplets generated from toilets during urination as a possible vehicle of carbapenem-resistant Klebsiella pneumoniae.

BACKGROUND: In the health care setting, infection control actions are fundamental for containing the dissemination of multidrug-resistant bacteria (MDR). Carbapenemase-producing Enterobacterales (CPE), especially Klebsiella pneumoniae (CR-KP), can spread among patients, although the dynamics of transmission are not fully known. Since CR-KP is present in wastewater and microorganisms are not completely removed from the toilet bowl by flushing, the risk of transmission in settings where toilets are shared should be addressed. We investigated whether urinating generates droplets that can be a vehicle for bacteria and explored the use of an innovative foam to control and eliminate this phenomenon. METHODS: To study droplet formation during urination, we set up an experiment in which different geometrical configurations of toilets could be reproduced and customized. To demonstrate that droplets can mobilize bacteria from the toilet bowl, a standard ceramic toilet was contaminated with a KPC-producing Klebsiella pneumoniae ST101 isolate. Then, we reproduced urination and attached culture dishes to the bottom of the toilet lid for bacterial colony recovery with and without foam. RESULTS: Rebound droplets invariably formed, irrespective of the geometrical configuration of the toilet. In microbiological experiments, we demonstrated that bacteria are always mobilized from the toilet bowl (mean value: 0.11 ± 0.05 CFU/cm2) and showed that a specific foam layer can completely suppress mobilization. CONCLUSIONS: Our study demonstrated that droplets generated from toilets during urination can be a hidden source of CR-KP transmission in settings where toilets are shared among colonized and noncolonized patients.

Long-term safety and efficacy studies of epinephrine HFA metered-dose inhaler (Primatene® Mist): a two-stage randomized controlled trial.

Objective: A new epinephrine hydrofluoroalkane (HFA) asthma metered-dose inhaler (MDI) was reformulated to replace the previously marketed epinephrine chlorofluorocarbon (CFC) MDI. In addition to the HFA propellant change, several enhanced modifications (i.e. changed from solution to suspension, 43% dose reduction, etc.) were made to the formulation of epinephrine HFA MDI. This study evaluates the 6-month long-term safety and efficacy profile of the new epinephrine HFA MDI.Method: The long-term safety study consists of two 3-month, multi-center, double- or evaluator-blinded, parallel-group, placebo, and active controlled stages. In each stage, subjects aged ≥12 years with intermittent or mild-to-moderate persistent asthma were randomized to receive epinephrine HFA (2 × 125 mcg/inhalation), placebo HFA, or epinephrine CFC (2 × 220 mcg/inhalation). Bronchodilator efficacy was assessed in Stage 1 and was determined primarily by the change in the forced expiratory volume in 1 s (ΔFEV1) at Week 12, relative to the same day baseline.Results: The primary efficacy endpoint (AUC0-6hrs of %ΔFEV1 at Week 12) for epinephrine HFA (47.3 ± 54.2) closely paralleled those for the active control, epinephrine CFC (41.0 ± 43.4). Both groups were found to be overall comparable in bronchodilator efficacy. Both also showed low incidence rates of AEs with tremor being most commonly reported for epinephrine HFA. All AEs found were non-serious and non-significant. The observed changes in vital signs, ECG, serum glucose, and potassium were minimal and not clinically relevant.Conclusion: This study demonstrated that the new epinephrine HFA is overall comparable, in both safety and efficacy, to the previous epinephrine CFC.

Sustainability in Inhaled Drug Delivery.

Asthma and chronic obstructive pulmonary disease (COPD) are amongst the most common chronic diseases worldwide, and are largely preventable by improving the quality of the air we breathe. The most commonly deployed treatment, the metered dose inhaler (MDI), uses hydrofluorocarbon propellants, which are powerful greenhouse gases that contribute disproportionately to the climate crisis. Alternative treatment strategies are required if we are to avoid contributing to the worst effects of climate change. These strategies include promoting non-pharmacological therapies like smoking cessation and pulmonary rehabilitation; empowering patients to gain better disease control through written management plans and encouraging preventer, rather than reliever therapies. Pharmacological strategies include: improving inhaler technique and spacer use; minimising propellant release by using smaller volume MDIs and simpler dosing regimes; dose counters to prevent waste; switching to low global warming potential inhalers; and inhaler recycling. There are also opportunities to improve disease control alongside reduced greenhouse gas emissions, including better matching of patients' devices to inhaler technique rather than defaulting to MDIs, stopping unnecessary inhaled steroids in COPD and maintenance and reliever therapy in asthma. New, lower global warming potential propellants are on the horizon, and their introduction could offer a golden opportunity to enhance MDIs usability and sustainability by making them refillable, integrating whistles to optimise inhalation technique, adding integrated caps, optimising materials for recycling and adding dose counters to all MDIs.

Pharmacokinetic Study of Epinephrine Hydrofluoroalkane (Primatene MIST) Metered-Dose Inhaler.

Background: Primatene® MIST CFC, an epinephrine metered-dose inhaler (MDI), was discontinued from the market owing to environmental concerns from its use of chlorofluorocarbon (CFC) propellant. As a result, a new epinephrine MDI was developed using hydrofluoroalkane (HFA) propellant. This article reports the pharmacokinetic (PK) profile of the newly Food and Drug Administration-approved epinephrine HFA MDI. Methods: A randomized, evaluator-blinded, active-controlled, single-dose, two-arm crossover study was conducted to evaluate the PK profile of epinephrine HFA (Primatene® MIST) and epinephrine CFC (Primatene® MIST CFC) in 23 healthy volunteers to characterize the epinephrine absorption extent and rate. The study was performed at a high dose of five times the normal dose to obtain measurable plasma epinephrine levels. Plasma epinephrine levels were measured and safety was assessed by adverse events (AEs), vital signs, clinical laboratory tests, and physical examinations. Results: Epinephrine HFA demonstrated a greater systemic drug exposure (greater area under the curve) than that of epinephrine CFC (∼37% higher). The Cmax occurred at ∼2 minutes and was significantly higher in the epinephrine HFA group (0.18 ng/mL) compared with the CFC version (0.046 ng/mL) at normal dose. Within 20 minutes, both groups demonstrated comparable plasma epinephrine levels. No clinically significant adverse effects were found to be associated with epinephrine HFA, even after an ultrahigh dose (i.e., 10 inhalations). Conclusions: The systemic exposure of epinephrine HFA was found to be higher for the first 20 minutes, and then comparable with epinephrine CFC. Minimal AEs were found in this study despite the very high 1250-2200 µg inhaled doses (i.e., 10 inhalations) used for PK characterization.

A Dose-Ranging Study of Epinephrine Hydrofluroalkane Metered-Dose Inhaler (Primatene® MIST) in Subjects with Intermittent or Mild-to-Moderate Persistent Asthma.

Background: Two sequential single-dose crossover dose-ranging studies were performed to evaluate the clinical efficacy and safety profile of epinephrine hydrofluroalkane (HFA) metered-dose inhaler (MDI) formulation at various doses in subjects with asthma. Methods: In these multicenter, multiarm, double-blinded, or evaluator-blinded studies, subjects were randomized to receive the epinephrine HFA (Primatene® MIST HFA) MDI medication at doses ranging from 90 to 440 µg/dose, as well as to a placebo (PLA) control and an active control of epinephrine CFC (chlorofluorocarbon) MDI (Primatene® MIST CFC) at 220 µg/inhalation. Results: Spirometry testing for FEV1 (Forced Expiratory Volume in one second) demonstrated statistically significant improvements over PLA for epinephrine HFA MDI at all doses above 125 µg, as the amount out of the actuator (i.e., mouthpiece). The efficacy results for epinephrine HFA MDI in the dose range of 125-250 µg were also comparable to epinephrine CFC MDI (220 µg/inh). Safety assessments demonstrated minimal safety concerns for all treatment groups. No notable safety differences were observed between the studied doses of epinephrine HFA MDI and the active control formulation of epinephrine CFC MDI. Conclusion: The findings indicate that epinephrine HFA MDI provided clinically significant bronchodilator efficacy with minimal safety concerns in a dose range of 125-250 µg. These findings confirmed the optimal treatment doses of 125-250 µg that were appropriate for use in longer term 12 and 26 week chronic dosing studies of epinephrine HFA MDI for patients with intermittent or mild to moderate persistent asthma. Clinical trials registration number: NCT01025648.

"Out of the box" solution for skin problems due to glucose-monitoring technology in youth with type 1 diabetes: real-life experience with fluticasone spray.

BACKGROUND: Use of a continuous glucose-monitoring system (CGMS) in the management of type 1 diabetes (T1D) may cause local skin irritation. OBJECTIVE: To examine the effects of fluticasone propionate aqueous nasal solution (nsFP), sprayed topically prior to CGMS insertion among youth with T1D. METHODS: This is a case series observational report, including real-life 6-month follow-up data from one pediatric diabetes center. All patients suffering from local skin irritation due to CGMS adhesives were offered prevention form skin irritation by spraying 2 puffs of nsFP on the skin area prior to adhesion of CGMS. Data were collected from their charts after 6 months. Outcome measures included the difference in degree of skin irritation, number of days of CGMS use, BMI SDS, mean glucose, and HbA1c, prior to use and during 6 months after use. RESULTS: Twelve patients used nsFP prior to CGMS insertion, mean age 8.6 ± 4.9 years and 66.7% males. Ten patients, median age 6.1 years (5.3-9.5) and 56% males, continued using nsFP for a mean of 0.56 ± 0.11 years, with no recurrence of local irritation nor dermatitis to same adhesive material. No differences were found before and after use of nsFP in CGMS mean glucose 180 mg/dl (153-202) versus 165 mg/dl (150-192). BMI SDS was slightly higher 0.44 (- 0.9-1.2) versus 0.25 (- 0.47-1.06), P = 0.05. CONCLUSIONS: This small-scale, single-site description of a simple intervention by nsFP and favorable outcome provides valuable insight for a simple solution for skin irritation and dermatitis in the pediatric population with T1D.

Drug distribution transients in solution and suspension-based pressurised metered dose inhaler sprays.

This paper presents in situ time-resolved drug mass fraction measurements in pressurised metered dose inhaler (PMDI) sprays, using a novel combination of synchrotron X-ray fluorescence and scattering. Equivalent suspension and solution formulations of ipratropium bromide in HFA-134a propellant were considered. Measurements were made both inside the expansion chamber behind the nozzle orifice, and in the first few millimeters of the spray where droplet and particle formation occur. We observed a consistent spike in drug mass fraction at the beginning of the spray when the first fluid exits the nozzle orifice. Approximately 20% of the total delivered dose exits the nozzle in the first 0.1 s of the spray. The drug mass fraction in the droplets immediately upon exiting the nozzle peaked at approximately 50% of the canister mass fraction, asymptoting to approximately 20% of the canister concentration. The effect is due to a change in the drug mass fraction inside the droplets, rather than changes in droplet size or distribution. The transient was found to originate inside the expansion chamber. We propose that this effect may be a major contributor to low delivery efficiency in PMDIs, and have important implications for oropharyngeal deposition and inhalation technique. This highlights the importance of expansion chamber and nozzle design on the structure of PMDI sprays, and indicates areas of focus that may lead to improvement in drug delivery outcomes.

Bioavailability of Beclometasone From Two HFA-BDP Formulations With a Spacer.

BACKGROUND: The drug delivery characteristics of each inhaler/spacer combination are unique. The spacer size as well as the presence of electrostatic charge greatly influence the inhaler dose emission and in vivo delivery. Using a previously developed urinary pharmacokinetic method, we have measured the relative lung and systemic bioavailability of beclometasone dipropionate (BDP) after inhalation from 2 hydrofluroalkane-beclometasone dipropionate (HFA-BDP) formulations when used with a spacer. METHODS: 12 healthy volunteers received 8 randomized doses, separated by 7 d, of inhaled of BDP with either the Clenil pressurized metered-dose inhaler (pMDI; 250 µg) or the breath-actuated Qvar Easi-Breathe inhaler (100 µg), used alone or with a spacer. The urinary amounts of BDP excreted and retained in the spacer were assayed using a liquid chromatographic mass spectrometer. The spacer was assessed after washing with a detergent solution that was either rinsed or not rinsed with water. In addition, the aerodynamic characterization of each inhaler/spacer combination was assessed using the Andersen Cascade Impactor operated at 28 L/min using a 4-L inhalation volume. The amount of BDP deposited in the induction port, spacer, and various Anderson Cascade Impactor stages were determined. RESULTS: The in vivo 30-min urinary excretion and the in vitro fine particle dose results were only slightly affected by adding the spacer to the Clenil pMDI or the Qvar Easi-Breathe inhaler. However, the spacer significantly reduced drug particle impaction in the oropharynx and minimized deposition in the gastrointestinal tract. Therefore, using spacers with BDP inhalers is associated with a more favorable therapeutic ratio because it has little effect on lung dose, but it significantly reduced throat deposition. An improved lung deposition was achieved with non-rinsed spacers compared to spacers rinsed with water. CONCLUSION: The difference in the BDP particle size between formulations as well as spacer size greatly affected drug deposition in different regions of the respiratory tract.

Amorphous pullulan trehalose microparticle platform for respiratory delivery.

Spray drying biologics and small-molecule drugs can increase their thermal stability relative to liquid dosage forms and allow for widespread distribution to developing countries without cold chain infrastructure. In this study, pullulan trehalose powder is spray dried for inhalation. The powder is characterized in terms of manufacturability, physical stability, device compatibility, and aerosol performance. The manufacturability is demonstrated by reasonable spray drying yield and powder flowability. The powder has relatively low cohesiveness and high compressibility without semi-elastic deformation. Short-term physical stability for ambient temperature dry storage and 40 °C storage in commercial pressurized metered-dose inhaler propellants HFA 134a and HFA 227 is shown. A theoretical model predicts a high glass transition temperature near the surface of the microparticles where biologics are expected to reside. Emission from a commercial dry powder inhaler demonstrates high dispersibility, optimal size for inhalation, and adequate total lung dose, exceeding many commercial inhalation devices. The powder can be filled, stored, and actuated from a pressurized metered-dose inhaler without changes in particle morphology or solid phase. The pullulan trehalose platform thus appears promising for respiratory delivery.