Peter Hanson Hirst

Improved Lung Delivery from a Passive Dry Powder Inhaler Using an Engineered PulmoSphere® Powder

AbstractPurpose. To assess the pulmonary deposition and pharmacokinetics of an engineered PulmoSphere® powder relative to standard micronized drug when delivered from passive dry powder inhalers (DPIs). Methods. Budesonide PulmoSphere (PSbud) powder was manufactured using an emulsion-based spray-drying process. Eight healthy subjects completed 3 treatments in crossover fashion: 370 μg budesonide PulmoSphere inhaled from Eclipse® DPI at target PIF of 25 L·min-1 (PSbud25), and 50 L·min-1 (PSbud50), and 800 μg of pelletized budesonide from Pulmicort® Turbuhaler® at 60 L·min-1(THbud60). PSbud powder was radiolabeled with 99mTc and lung deposition determined scintigraphically. Plasma budesonide concentrations were measured for 12 h after inhalation. Results. Pulmonary deposition (mean ± sd) of PSbud was 57 ± 7% and 58 ± 8% of the nominal dose at 25 and 50 L·min-1, respectively. Mean peak plasma budesonide levels were 4.7 (PSbud25), 4.0 (PSbud50), and 2.2 ng·ml-1 (THbud60). Median tmax was 5 min after both PSbud inhalations compared to 20 min for Turbuhaler (P < 0.05). Mean AUCs were comparable after all inhalations, 5.1 (PSbud25), 5.9 (PSbud50), and 6.0 (THbud60) ng·h·ml-1. The engineered PSbud powder delivered at both flow rates from the Eclipse® DPI was twice as efficiently deposited as pelletized budesonide delivered at 60 L·min-1 from the Turbuhaler. Intersubject variability was also dramatically decreased for PSbud relative to THbud. Conclusion. Delivery of an engineered PulmoSphere formulation is more efficient and reproducible than delivery of micronized drug from passive DPIs.

In Vivo Lung Deposition of Hollow Porous Particles from a Pressurized Metered Dose Inhaler

AbstractPurpose: PulmoSphere™ particles are specifically engineered for delivery by the pulmonary route with a hollow and porous morphology, physical diameters < 5 μm, and low tap densities (circa 0.1 g.cm-3). Deposition of PulmoSphere particles in the human respiratory tract delivered by pressurized metered dose inhaler (pMDI) was compared with deposition of a conventional micronized drug pMDI formulation. Methods: Nine healthy nonsmoking subjects (5 male, 4 female) completed a two-way crossover gamma scintigraphic study, assessing the lung and oropharyngeal depositions of albuterol sulfate, formulated as 99mTc-radiolabeled PulmoSphere particles or micronized particles (Ventolin EvohalerTM, GlaxoSmithKline, Ltd.) suspended in HFA-134a propellant. Results: Mean (standard deviation) lung deposition, (% ex-valve dose) was doubled for the PulmoSphere formulation compared with Evohaler pMDI (28.5 (11.3) % vs. 14.5 (8.1) %, P < 0.01), whereas oropharyngeal deposition was reduced (42.6 (9.0) % vs. 72.0 (8.0) %, P < 0.01). Both PulmoSphere and Evohaler pMDIs gave uniform deposition patterns within the lungs. Conclusions: These data provided “proof of concept” in vivo for the PulmoSphere technology as a method of improving targeting of drugs to the lower respiratory tract from pMDIs, and suggested that the PulmoSphere technology may also be suitable for the delivery of systemically acting molecules absorbed via the lung.

Radionuclide imaging technologies and their use in evaluating asthma drug deposition in the lungs.

Whole lung and regional lung deposition of inhaled asthma drugs in the lungs can be quantified using either two-dimensional or three-dimensional radionuclide imaging methods. The two-dimensional method of gamma scintigraphy has been the most widely used, and is currently considered the industry standard, but the three-dimensional methods (SPECT, single photon emission computed tomography; and PET, positron emission tomography) give superior regional lung deposition data and will undoubtedly be used more frequently in future. Recent developments in radionuclide imaging are described, including an improved algorithm for assessing regional lung deposition in gamma scintigraphy, and a patent-protected radiolabelling method (TechneCoat), applicable to both gamma scintigraphy and SPECT. Radionuclide imaging data on new inhaled asthma products provide a milestone assessment, and the data form a bridge between in vitro testing and a full clinical trials program, allowing the latter to be entered with increased confidence.

Deposition and pharmacokinetics of flunisolide delivered from pressurized inhalers containing non-CFC and CFC propellants.

Our objective was to assess the deposition and pharmacokinetics of a novel formulation of flunisolide (Aerobid, Forest Laboratories) in hydrofluoroalkane (HFA) 134a delivered by pressurized metered dose inhaler (pMDI). The design was a two-way crossover investigation in 12 healthy male subjects comparing HFA-134a flunisolide by pMDI versus pMDI plus 50 mL spacer device. Four of these subjects also took part in a two-way crossover investigation comparing chlorofluorocarbon (CFC) flunisolide pMDI versus pMDI plus Aerochamber holding chamber. The imaging technique of gamma scintigraphy was used to quantify total and regional lung deposition of flunisolide. Plasma levels of flunisolide and its major metabolite (6beta-OH flunisolide) were also determined. The spacer and Aerochamber reduced oropharyngeal deposition dramatically for both the HFA and CFC products (mean 59.8 to 14.9% (p < 0.01) of ex-valve (metered) dose for HFA product; 66.3 to 12.3% (p < 0.01) of ex-valve dose for CFC product) owing to deposition of part of the dose on the walls of the add-on devices themselves. Lung deposition averaged 22.6 and 40.4% (p < 0.01) of the ex-valve dose for the HFA formulation used with pMDI alone and with pMDI plus spacer. Mean lung deposition of the CFC formulation delivered via the Aerochamber (mean 23.4%) was higher than that for the CFC pMDI alone (mean 17.0%), but this difference was not statistically significant. Lung deposition expressed as percentage ex-device (delivered) dose averaged 68.3% for HFA pMDI plus spacer and 19.7% for CFC pMDI. Plasma levels of flunisolide were higher for the pMDI plus spacer than for pMDI alone, reflecting higher lung deposition via the spacer, but plasma levels of the 6beta-OH flunisolide metabolite were higher for the pMDI alone as a consequence of higher oropharyngeal deposition. When delivered via the spacer, pulmonary targeting of the flunisolide HFA formulation was improved compared with the CFC formulation, which should benefit patients by providing satisfactory asthma therapy from a much-reduced delivered dose of flunisolide.

Regional lung deposition of a technetium 99m-labeled formulation of mometasone furoate administered by hydrofluoroalkane 227 metered-dose inhaler.

BACKGROUND A new inhaled suspension formulation of mometasone furoate (MF), a potent corticosteroid with minimal systemic availability, has been developed for the treatment of asthma. This formulation is delivered by metered-dose inhaler (MDI) using the nonchlorofluorocarbon propellant hydrofluoroalkane 227 (HFA-227). OBJECTIVE The primary goal of this study was to determine the respiratory tract deposition of this formulation of MF. A secondary objective was to measure plasma concentrations of MF and a putative metabolite, 6-X-OH MF, to determine the systemic exposure to corticosteroid. METHODS This was a single-dose, open-label study in which 200 microg of technetium 99m (99mTc)-radiolabeled MF was administered to patients with asthma. Gamma scintigraphy was used to quantify lung, oropharyngeal, stomach, and MDI mouthpiece deposition patterns of MF. RESULTS Eleven patients, aged 21 to 47 years, with a history of asthma were enrolled in and completed the study. The mean (+/- SD) whole lung deposition of MF was 13.9%+/-5.7% of the metered (ex-valve) dose. The central lung zone received 5.3%+/-2.8% of the dose; the intermediate zone received 4.7%+/-1.9%; and peripheral lung deposition was 4.0%+/-1.5%. The mean (+/- SD) ratio of peripheral to central lung deposition was 0.8+/-0.2. Oropharyngeal deposition was 79.1%+/-8.7% of the ex-valve dose, with 6.3%+/-7.8% deposited on the MDI mouthpiece and 0.7%+/-0.5% exhaled. The majority of plasma samples taken for analysis of MF and 6-13-OH MF concentrations were below the limit of quantification (50 pg/mL) in all patients after inhalation of 200 microg 99mTc-labeled ME CONCLUSION: The lung deposition of MF when administered via HFA-227 MDI is comparable to the 10 to 20% lung deposition seen with other corticosteroid suspension for- mulations administered by MDI that have demonstrated effectiveness in the treatment of asthma.

Deposition and pharmacokinetics of budesonide from the Miat Monodose inhaler, a simple dry powder device

Dry powder inhalers (DPIs) are used to deliver asthma drugs to patients, but lung deposition may depend upon the degree of inspiratory effort. The pulmonary deposition of the glucocorticosteroid budesonide (SMB-Galephar) has been assessed in 12 asthmatic patients when delivered by the Monodose inhaler (Miat, Milan, Italy); the Pulmicort Turbuhaler DPI (AstraZeneca, Lund, Sweden) was used as a comparator product. Patients inhaled from each device with maximal or sub-maximal inspiratory effort: Monodose inhaler 90 vs 45 l/min; Turbuhaler DPI 60 vs 30 l/min. The formulations were radiolabelled with (99m)Tc, and deposition of budesonide was quantified by gamma scintigraphy. Mean (SD) whole lung deposition for the Monodose inhaler (% capsule dose), was independent of inspiratory effort (maximal: 21.4 (4.3)%; sub-maximal: 21.4 (7.5)%), while lung deposition for the Turbuhaler DPI (% metered dose) fell significantly with decreasing inspiratory effort (maximal: 25.1 (6.1)%; sub-maximal: 18.5 (6.5)%; P<0.05). The plasma concentrations of budesonide showed the same trends as the whole lung deposition data. The Monodose inhaler showed inspiratory effort-independent drug delivery characteristics, and could prove be a valuable low-cost alternative to more complex devices such as the Turbuhaler DPI. The Monodose inhaler may be especially useful in groups of patients unable to inhale maximally through DPIs, including young children and adult patients with severe respiratory impairment.

Radionuclide Imaging for Assessing Pulmonary Drug Delivery

The radionuclide imaging technique of gamma scintigraphy plays an important role in evaluating the performance of new inhaled drug products in humans. Some recent improvements in methodology are described, relating to assessment methods for both whole lung deposition and regional lung deposition. The lungs have been divided into six lung-shaped regions, and an Airway Penetration Factor is defined for each region. This allows regional lung deposition patterns to be examined in greater detail than was previously possible. Transmission scans using a large flood field source are used to build up an ‘attenuation map’, allowing separate tissue attenuation correction factors to be defined for the mouth, pharynx, six lung regions, esophagus/trachea and stomach. This allows lung and oropharyngeal depositions to be quantified in a more fundamentally correct manner, either as percentage of dose or as mass of drug. These improved methodologies should enhance the value of radionuclide imaging studies, ensuring that they remain a key part of the drug development process.